feat(drafts): add bot_drafts schema, automatic table bootstrap, and sync REST endpoints

backend/app/main.py

@@ -27,6 +27,7 @@ from app.db.engine import AsyncSessionLocal, engine
 from app.db.init_db import (
     ensure_attachment_table,
     ensure_audit_table,
+    ensure_bot_drafts_table,
     ensure_drop_category_tables,
     ensure_dashboard_tables,
     ensure_material_topic_column,
@@ -107,6 +108,7 @@ async def lifespan(_app: FastAPI):
     await ensure_v26(engine)
     await ensure_audit_table(engine)
     await ensure_drop_category_tables(engine)
+    await ensure_bot_drafts_table(engine)
     task = asyncio.create_task(_auto_expire_loop()) if settings.AUTO_EXPIRE_ENABLED else None
     try:
         yield
@@ -233,12 +235,15 @@ from app.routers.auth import router as _auth_router  # noqa: E402
 # attach an Authorization header to <iframe>/<img> loads, so the two file GET
 # routes accept a short-lived signed ?t= token as well as a Bearer session.
 from app.routers.files import router as _files_router  # noqa: E402
+from app.routers.drafts import router as _drafts_router  # noqa: E402
 
 for router in ROUTERS:
     if router is _auth_router:
         app.include_router(router, prefix=API_V1_PREFIX)
     elif router is _files_router:
         app.include_router(router, prefix=API_V1_PREFIX)
+    elif router is _drafts_router:
+        app.include_router(router, prefix=API_V1_PREFIX)
     else:
         app.include_router(router, prefix=API_V1_PREFIX, dependencies=[Depends(get_current_user)])