Slice 6: notifications per §15

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/app/main.py

@@ -14,7 +14,7 @@ from fastapi import APIRouter, FastAPI, HTTPException, Request
 from fastapi.responses import RedirectResponse
 from starlette.middleware.sessions import SessionMiddleware
 
-from . import api as api_routes, auth, cache, db, providers as providers_mod, webhooks
+from . import api as api_routes, auth, cache, db, digest, providers as providers_mod, webhooks
 from .bot import Bot
 from .config import load_config
 from .gitea import Gitea
@@ -31,6 +31,7 @@ async def lifespan(app: FastAPI):
     gitea = Gitea(config)
     bot = Bot(gitea)
     reconciler = cache.Reconciler(config, gitea)
+    digest_sched = digest.DigestScheduler()
 
     # §18 carryover: the multi-provider LLM abstraction. Provider
     # construction can fail (missing key, wrong env value) — if it does,
@@ -53,10 +54,12 @@ async def lifespan(app: FastAPI):
     app.include_router(webhooks.make_router(config, gitea))
 
     reconciler.start()
+    digest_sched.start()
     log.info("RFC app started — meta repo %s/%s", config.gitea_org, config.meta_repo)
     try:
         yield
     finally:
+        await digest_sched.stop()
         await reconciler.stop()
         await gitea.close()