feat(android): 设计系统与五个页面重做，并补齐升级工单、邀请、看板

此前安卓只到"能登录、能看列表"，且从没编译过。这轮把它做到与 Web 同构：

- Theme.kt 与 Tailwind 同一套色板与字号阶；新增 Widgets.kt（状态 pill、
  卡片、按钮、头像、空态、时间与 action 的中文映射、错误码文案）
- 新增 AppFrame.kt（顶栏工作区 + 未读角标 + 底部四 tab）与
  TaskDetailSheet / BoardScreen / MembersScreen
- 重写任务、工单、知识三页与登录、首页；任务详情里补上「升级成工单」
  和「沉淀成知识」——这两个入口此前只有 Web 有，是真正的功能欠账
- 看板不做拖拽：一列已占 76% 屏宽，拖拽命中率太差，改为点卡片选目标列
- 修运行期 bug：workspaces/members 按 List 解析而服务端返回 {items:[...]}；
  消息区被手势条遮挡；升级工单候选人里出现自己；priority=0 显示"无"
- android/scripts/emulator.ps1 固化构建+装机+起模拟器；assembleDebug 出 APK

已在 API 35 模拟器上逐页跑通并截图（见 2.Design/screens/android-*.png）。

android/app/src/main/java/com/dadao/task/MainActivity.kt

@@ -1,8 +1,10 @@
 package com.dadao.task
 
+import android.content.Intent
 import android.os.Bundle
 import androidx.activity.ComponentActivity
 import androidx.activity.compose.setContent
+import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Surface
@@ -13,15 +15,20 @@ import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.platform.LocalContext
 import com.dadao.task.data.Api
 import com.dadao.task.data.TokenStore
 import com.dadao.task.data.Workspace
+import com.dadao.task.ui.BoardScreen
 import com.dadao.task.ui.DadaoTheme
 import com.dadao.task.ui.HomeScreen
 import com.dadao.task.ui.KnowledgeScreen
 import com.dadao.task.ui.LoginScreen
+import com.dadao.task.ui.MembersScreen
 import com.dadao.task.ui.TaskListScreen
 import com.dadao.task.ui.TicketsScreen
+import com.dadao.task.ui.WorkspaceScaffold
+import com.dadao.task.ui.WorkspaceTab
 
 class MainActivity : ComponentActivity() {
 
@@ -30,22 +37,37 @@ class MainActivity : ComponentActivity() {
         setContent {
             DadaoTheme {
                 Surface(Modifier.fillMaxSize(), color = MaterialTheme.colorScheme.background) {
-                    AppRoot()
+                    AppRoot(joinUri = intent?.dataString)
                 }
             }
         }
     }
 }
 
-private enum class Screen { Splash, Login, Home, Tasks, Tickets, Knowledge }
+private enum class Screen { Splash, Login, Home, Workspace }
+
+/** 从 https://dadaotask.com/join/<workspaceId>/<code> 里拆出工作区与邀请码。 */
+private fun parseJoin(uri: String?): Pair<String, String>? {
+    if (uri.isNullOrBlank()) return null
+    val parts = uri.trimEnd('/').split("/")
+    val idx = parts.indexOf("join")
+    if (idx < 0 || parts.size < idx + 3) return null
+    val ws = parts[idx + 1]
+    val code = parts[idx + 2]
+    if (ws.length < 10 || code.length < 4) return null
+    return ws to code
+}
 
 @Composable
-private fun AppRoot() {
-    val context = androidx.compose.ui.platform.LocalContext.current
+private fun AppRoot(joinUri: String?) {
+    val context = LocalContext.current
     val tokens = remember { TokenStore(context) }
     val api = remember { Api(tokens) }
     var screen by remember { mutableStateOf(if (tokens.isLoggedIn) Screen.Splash else Screen.Login) }
+    var pendingJoin by remember { mutableStateOf(parseJoin(joinUri)) }
     var current by remember { mutableStateOf<Workspace?>(null) }
+    var tab by remember { mutableStateOf(WorkspaceTab.Tasks) }
+    var unread by remember { mutableStateOf(0) }
 
     // 有本地令牌就先静默校验一次：令牌过期/被吊销要退回登录页，而不是进了主页再崩。
     LaunchedEffect(screen) {
@@ -60,8 +82,28 @@ private fun AppRoot() {
         }
     }
 
+    // 邀请链接：登录之后自动加入，加入完直接进那个工作区。
+    LaunchedEffect(screen, pendingJoin) {
+        val join = pendingJoin ?: return@LaunchedEffect
+        if (screen != Screen.Home) return@LaunchedEffect
+        runCatching { api.join(join.first, join.second) }
+            .onSuccess {
+                current = it
+                tab = WorkspaceTab.Tasks
+                pendingJoin = null
+                screen = Screen.Workspace
+            }
+            .onFailure { pendingJoin = null }
+    }
+
+    // 工单未读数：进工作区就拉一次，切页面时再刷。
+    LaunchedEffect(current?.id, tab) {
+        val ws = current ?: return@LaunchedEffect
+        unread = api.unreadCount(ws.id)
+    }
+
     when (screen) {
-        Screen.Splash -> Unit // 校验中，空白过渡即可
+        Screen.Splash -> Unit
         Screen.Login -> LoginScreen(api = api, onLoggedIn = { screen = Screen.Home })
         Screen.Home -> HomeScreen(
             api = api,
@@ -71,37 +113,29 @@ private fun AppRoot() {
             },
             onOpenWorkspace = { ws ->
                 current = ws
-                screen = Screen.Tasks
+                tab = WorkspaceTab.Tasks
+                screen = Screen.Workspace
             },
         )
-        Screen.Tasks -> {
+        Screen.Workspace -> {
             val ws = current
             if (ws == null) {
                 screen = Screen.Home
             } else {
-                TaskListScreen(
-                    api = api,
+                WorkspaceScaffold(
                     workspace = ws,
-                    onBack = { screen = Screen.Home },
-                    onOpenTickets = { screen = Screen.Tickets },
-                    onOpenKnowledge = { screen = Screen.Knowledge },
-                )
-            }
-        }
-        Screen.Tickets -> {
-            val ws = current
-            if (ws == null) {
-                screen = Screen.Home
-            } else {
-                TicketsScreen(api = api, workspace = ws, onBack = { screen = Screen.Tasks })
-            }
-        }
-        Screen.Knowledge -> {
-            val ws = current
-            if (ws == null) {
-                screen = Screen.Home
-            } else {
-                KnowledgeScreen(api = api, workspace = ws, onBack = { screen = Screen.Tasks })
+                    tab = tab,
+                    unread = unread,
+                    onTab = { tab = it },
+                    onBackHome = { screen = Screen.Home },
+                ) {
+                    when (tab) {
+                        WorkspaceTab.Tasks -> TaskListScreen(api = api, workspace = ws)
+                        WorkspaceTab.Tickets -> TicketsScreen(api = api, workspace = ws)
+                        WorkspaceTab.Knowledge -> KnowledgeScreen(api = api, workspace = ws)
+                        WorkspaceTab.Members -> MembersScreen(api = api, workspace = ws)
+                    }
+                }
             }
         }
     }