feat(knowledge): 知识改成备忘录形态，一次写全 + 三级分类，抽屉加宽

知识以前只能"填个标题就完成"，正文、标签、归类都要点进去再补。现在新建
就是一张完整的备忘录：标题、类型、分类、标签、正文一次写完，存完直接打开
详情继续编辑；知识页左侧多了工作区三级分类树，可按分类子树 / 未分类 / 标签
筛选。凡是填信息的抽屉都加宽了，还能一键展开整屏。

后端
- 新增 `knowledge_category`（迁移 0007）：`workspace_id NOT NULL` + 自引用
  `parent_id`、`depth` 1..3 检查约束、同层重名唯一索引（lower(name)）、
  RLS 策略与 `dadao_app` 授权；`knowledge_doc.category_id` 外键 ON DELETE
  SET NULL。
- 新增 `/knowledge/categories` 增删改查：超三级 `7007`、同层重名 `7008`、
  跨租户或不存在 `7006`；`move=true` 才改父级，成环与移动后超过三级的子树
  一律拒绝，删除有知识的分类要 `force=true`（知识变未分类）。
- 知识列表支持 `category_id`（含子树）、`uncategorized`、`tag`；输出带
  `category`（含 `path` / `full_path`）。
- PATCH 只改分类或标签也会推进 `version`，避免"只动标签"之后下次保存撞
  乐观锁 `4009`。

Web
- `Sheet` 增 `size="md/lg/xl"` 与展开整屏按钮；任务、工单、知识抽屉统一
  加宽（`TaskDetail` / `Tickets` / `Knowledge`）。
- 知识页：左侧三级分类树（新建、按子树筛选、未分类）、`KnowledgeComposer`
  一次写全新的备忘录、列表卡片露出分类路径与标签、详情抽屉里可直接改分类
  与标签。
- 抽屉详情只拉一次：重复的 effect 或迟到的响应不再覆盖用户正在敲的内容。

安卓
- `Api.kt`：分类模型与接口、新建/更新带 `tag_names`/`category_id`、
  列表带分类与标签筛选。
- 知识页重做：新建改为近全屏大对话框（标题/类型/分类/标签/正文），列表
  顶部按分类筛选，详情里能改分类与标签后单独保存。

文档与测试
- `2.Design/API.md`：5.1/5.3/5.4 补分类与筛选参数，新增 5.5 分类接口章节，
  错误码补 `7006`/`7007`/`7008`。
- `2.Design/ROADMAP-M0-M1.md`：新增 3.11（三级分类）、3.12（备忘录形态）。
- 新增 `backend/tests/test_knowledge_categories.py`（8 例）：备忘形态落库、
  三级到底、移动越界与成环、重名、按子树/未分类/标签/关键词筛选、删分类需
  `force`、跨租户隔离。
- 新增 `web/e2e/knowledge-notebook.mjs`（10 项，全绿）：建两级分类 → 一次
  写全 → 卡片与筛选 → 抽屉改标签/分类 → 正文落库 → 重名 7008。

验证：`pytest` 93 passed、`ruff check` / `ruff format --check` 全过、
`tsc --noEmit` 通过、`vite build` 通过、`knowledge-notebook.mjs` 10 项全绿。
安卓端本机只有 JDK 25，Gradle 8.7 / AGP 8.7.3 不支持，本次未做编译验证。

backend/tests/test_knowledge_categories.py

@@ -0,0 +1,280 @@
+"""知识库的"备忘录"形态：分类树、正文、标签、筛选。
+
+知识最容易做坏的地方，是把它做成"只填标题的任务"——那样的库三个月后没人会打开。
+所以这里断言的是：一条知识能装下正文和标签、能被归到三级分类里、能按分类和标签找回来。
+
+三条边界单独盯着：
+
+1. **三级到底**。第四级不是"更细"，是"找不到"；越界必须当场拒绝（7007）。
+2. **移动会带着子树一起动**。把一棵三层树挪到第二层下面，结果会是第五层，
+   这种操作要么重算层级、要么拒绝——这里选择拒绝，因为静默改层级同样会让人找不到。
+3. **删分类不删知识**。有内容时必须显式 `force`，否则容易点一下就把别人的整理工作打散。
+"""
+
+from __future__ import annotations
+
+from typing import Any
+
+import pytest
+from httpx import AsyncClient
+
+from .conftest import create_workspace, login, unwrap
+
+V1 = "/api/v1"
+
+
+def _code(resp: Any) -> int:
+    return int(resp.json().get("code", 0))
+
+
+async def _ws(client: AsyncClient) -> tuple[dict[str, Any], str]:
+    user = await login(client)
+    ws = await create_workspace(client, user, "知识库")
+    return user, ws["id"]
+
+
+async def _category(
+    client: AsyncClient, user: dict[str, Any], ws_id: str, name: str, parent_id: str | None = None
+) -> dict[str, Any]:
+    return unwrap(
+        await client.post(
+            f"{V1}/workspaces/{ws_id}/knowledge/categories",
+            json={"name": name, "parent_id": parent_id},
+            headers=user["headers"],
+        )
+    )
+
+
+async def _note(
+    client: AsyncClient,
+    user: dict[str, Any],
+    ws_id: str,
+    title: str,
+    *,
+    body: str = "",
+    tags: list[str] | None = None,
+    category_id: str | None = None,
+) -> dict[str, Any]:
+    return unwrap(
+        await client.post(
+            f"{V1}/workspaces/{ws_id}/knowledge",
+            json={
+                "title": title,
+                "body_md": body,
+                "doc_type": "note",
+                "tag_names": tags or [],
+                "category_id": category_id,
+            },
+            headers=user["headers"],
+        )
+    )
+
+
+async def _list(
+    client: AsyncClient, user: dict[str, Any], ws_id: str, **params: Any
+) -> list[dict[str, Any]]:
+    return unwrap(
+        await client.get(
+            f"{V1}/workspaces/{ws_id}/knowledge", params=params, headers=user["headers"]
+        )
+    )["items"]
+
+
+@pytest.mark.asyncio
+async def test_note_keeps_body_tags_and_category_path(client: AsyncClient) -> None:
+    user, ws_id = await _ws(client)
+    root = await _category(client, user, ws_id, "研发")
+    child = await _category(client, user, ws_id, "部署", root["id"])
+    leaf = await _category(client, user, ws_id, "回滚", child["id"])
+    assert leaf["depth"] == 3
+    assert leaf["full_path"] == "研发 / 部署 / 回滚"
+
+    doc = await _note(
+        client,
+        user,
+        ws_id,
+        "回滚前先停掉灰度",
+        body="# 步骤\n\n1. 停灰度\n2. 回滚镜像\n",
+        tags=["发布", "事故"],
+        category_id=leaf["id"],
+    )
+    assert doc["category"]["id"] == leaf["id"]
+    assert doc["category"]["full_path"] == "研发 / 部署 / 回滚"
+    assert {t["name"] for t in doc["tags"]} == {"发布", "事故"}
+
+    detail = unwrap(
+        await client.get(f"{V1}/workspaces/{ws_id}/knowledge/{doc['id']}", headers=user["headers"])
+    )
+    assert "停灰度" in detail["body_md"]
+    assert detail["category"]["full_path"] == "研发 / 部署 / 回滚"
+
+
+@pytest.mark.asyncio
+async def test_category_depth_stops_at_three(client: AsyncClient) -> None:
+    user, ws_id = await _ws(client)
+    l1 = await _category(client, user, ws_id, "一级")
+    l2 = await _category(client, user, ws_id, "二级", l1["id"])
+    l3 = await _category(client, user, ws_id, "三级", l2["id"])
+    resp = await client.post(
+        f"{V1}/workspaces/{ws_id}/knowledge/categories",
+        json={"name": "四级", "parent_id": l3["id"]},
+        headers=user["headers"],
+    )
+    assert resp.status_code == 422, resp.text
+    assert _code(resp) == 7007
+
+
+@pytest.mark.asyncio
+async def test_move_cannot_exceed_depth_or_loop(client: AsyncClient) -> None:
+    user, ws_id = await _ws(client)
+    a = await _category(client, user, ws_id, "A")
+    b = await _category(client, user, ws_id, "B", a["id"])
+    c = await _category(client, user, ws_id, "C", b["id"])
+    other = await _category(client, user, ws_id, "X")
+
+    # 把 A（下面还有 B、C）移到 C 下面：自己是自己的祖先
+    resp = await client.patch(
+        f"{V1}/workspaces/{ws_id}/knowledge/categories/{a['id']}",
+        json={"move": True, "parent_id": c["id"], "version": a["version"]},
+        headers=user["headers"],
+    )
+    assert resp.status_code in (409, 422), resp.text
+    assert _code(resp) == 7007
+
+    # 把 A 移到 X 下面：A 现在是一级，B、C 跟着下沉，C 会到第四级 -> 拒绝
+    resp = await client.patch(
+        f"{V1}/workspaces/{ws_id}/knowledge/categories/{a['id']}",
+        json={"move": True, "parent_id": other["id"], "version": a["version"]},
+        headers=user["headers"],
+    )
+    assert _code(resp) == 7007
+    del c, b
+
+
+@pytest.mark.asyncio
+async def test_rename_conflict_and_move_to_root(client: AsyncClient) -> None:
+    user, ws_id = await _ws(client)
+    a = await _category(client, user, ws_id, "研发")
+    b = await _category(client, user, ws_id, "市场")
+    dup = await client.post(
+        f"{V1}/workspaces/{ws_id}/knowledge/categories",
+        json={"name": "研发"},
+        headers=user["headers"],
+    )
+    assert dup.status_code == 409, dup.text
+    assert _code(dup) == 7008
+
+    child = await _category(client, user, ws_id, "部署", a["id"])
+    moved = unwrap(
+        await client.patch(
+            f"{V1}/workspaces/{ws_id}/knowledge/categories/{child['id']}",
+            json={"move": True, "parent_id": None, "version": child["version"]},
+            headers=user["headers"],
+        )
+    )
+    assert moved["parent_id"] is None
+    assert moved["depth"] == 1
+    assert moved["full_path"] == "部署"
+    del b
+
+
+@pytest.mark.asyncio
+async def test_list_filters_by_category_subtree_tag_and_search(client: AsyncClient) -> None:
+    user, ws_id = await _ws(client)
+    root = await _category(client, user, ws_id, "研发")
+    sub = await _category(client, user, ws_id, "部署", root["id"])
+    other = await _category(client, user, ws_id, "市场")
+
+    deep = await _note(
+        client,
+        user,
+        ws_id,
+        "灰度发布流程",
+        body="先停灰度再回滚",
+        tags=["发布"],
+        category_id=sub["id"],
+    )
+    await _note(
+        client, user, ws_id, "季度预算", body="市场预算表", tags=["财务"], category_id=other["id"]
+    )
+    loose = await _note(client, user, ws_id, "散记", body="还没归类", tags=["草稿"])
+
+    by_category = await _list(client, user, ws_id, category_id=root["id"])
+    assert {d["id"] for d in by_category} == {deep["id"]}
+    by_none = await _list(client, user, ws_id, uncategorized="true")
+    assert {d["id"] for d in by_none} == {loose["id"]}
+    assert {d["id"] for d in await _list(client, user, ws_id, tag="发布")} == {deep["id"]}
+    assert {d["id"] for d in await _list(client, user, ws_id, q="回滚")} == {deep["id"]}
+
+
+@pytest.mark.asyncio
+async def test_delete_category_needs_force_when_docs_exist(client: AsyncClient) -> None:
+    user, ws_id = await _ws(client)
+    cat = await _category(client, user, ws_id, "待清理")
+    doc = await _note(client, user, ws_id, "有主的东西", category_id=cat["id"])
+
+    blocked = await client.delete(
+        f"{V1}/workspaces/{ws_id}/knowledge/categories/{cat['id']}", headers=user["headers"]
+    )
+    assert blocked.status_code == 409, blocked.text
+    assert _code(blocked) == 7008
+
+    forced = unwrap(
+        await client.delete(
+            f"{V1}/workspaces/{ws_id}/knowledge/categories/{cat['id']}?force=true",
+            headers=user["headers"],
+        )
+    )
+    assert forced["uncategorized_docs"] == 1
+    detail = unwrap(
+        await client.get(f"{V1}/workspaces/{ws_id}/knowledge/{doc['id']}", headers=user["headers"])
+    )
+    assert detail["category"] is None
+
+
+@pytest.mark.asyncio
+async def test_category_is_tenant_scoped(client: AsyncClient) -> None:
+    owner, ws_id = await _ws(client)
+    intruder = await login(client)
+    other_ws = await create_workspace(client, intruder, "别人的工作区")
+    foreign = await _category(client, intruder, other_ws["id"], "他们的分类")
+
+    listed = unwrap(
+        await client.get(f"{V1}/workspaces/{ws_id}/knowledge/categories", headers=owner["headers"])
+    )
+    assert listed["items"] == []
+
+    # 用别的工作区的分类 id 建知识：应被当作"不存在"
+    resp = await client.post(
+        f"{V1}/workspaces/{ws_id}/knowledge",
+        json={"title": "越界", "category_id": foreign["id"]},
+        headers=owner["headers"],
+    )
+    assert resp.status_code == 404, resp.text
+    assert _code(resp) == 7006
+
+
+@pytest.mark.asyncio
+async def test_patch_knowledge_moves_and_clears_category(client: AsyncClient) -> None:
+    user, ws_id = await _ws(client)
+    cat = await _category(client, user, ws_id, "研发")
+    doc = await _note(client, user, ws_id, "一篇知识", category_id=cat["id"])
+
+    moved = unwrap(
+        await client.patch(
+            f"{V1}/workspaces/{ws_id}/knowledge/{doc['id']}",
+            json={"category_id": cat["id"], "tag_names": ["运维"], "version": doc["version"]},
+            headers=user["headers"],
+        )
+    )
+    assert moved["category"]["name"] == "研发"
+    assert {t["name"] for t in moved["tags"]} == {"运维"}
+
+    cleared = unwrap(
+        await client.patch(
+            f"{V1}/workspaces/{ws_id}/knowledge/{doc['id']}",
+            json={"clear_category": True, "version": moved["version"]},
+            headers=user["headers"],
+        )
+    )
+    assert cleared["category"] is None