feat(m0): 后端骨架 + Web/安卓前端骨架 + 设计文档

- backend: FastAPI 应用工厂、统一错误信封、JWT、短信登录、工作区/成员/邀请、幂等中间件
- alembic 0001: workspace/member/invitation/audit_log/app_user + RLS 策略 + 双角色 GRANT
- tests: 认证/工作区/租户隔离/幂等 四组用例（尚未在本机执行）
- web: React18+Vite 骨架（登录、工作区、邀请落地页）
- android: Compose 骨架（登录、工作区列表）
- 2.Design: PRODUCT-PLAN / ROADMAP-M0-M1 / NAMING / DEVELOPMENT

backend/alembic/script.py.mako

@@ -0,0 +1,27 @@
+"""${message}
+
+Revision ID: ${up_revision}
+Revises: ${down_revision | comma,n}
+Create Date: ${create_date}
+"""
+
+from __future__ import annotations
+
+from collections.abc import Sequence
+
+import sqlalchemy as sa
+from alembic import op
+${imports if imports else ""}
+
+revision: str = ${repr(up_revision)}
+down_revision: str | None = ${repr(down_revision)}
+branch_labels: str | Sequence[str] | None = ${repr(branch_labels)}
+depends_on: str | Sequence[str] | None = ${repr(depends_on)}
+
+
+def upgrade() -> None:
+    ${upgrades if upgrades else "pass"}
+
+
+def downgrade() -> None:
+    ${downgrades if downgrades else "pass"}