Slice 6: notifications per §15

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

backend/app/api.py

@@ -17,7 +17,7 @@ from typing import Any
 from fastapi import APIRouter, HTTPException, Request
 from pydantic import BaseModel, Field
 
-from . import api_branches, api_graduation, api_prs, auth, db, entry as entry_mod, cache
+from . import api_branches, api_graduation, api_notifications, api_prs, auth, db, entry as entry_mod, cache
 from .bot import Bot
 from .config import Config
 from .gitea import Gitea, GiteaError
@@ -55,6 +55,9 @@ def make_router(
     router.include_router(api_prs.make_router(config, gitea, bot, providers))
     # Slice 5: §13 graduation + §13.1 claim.
     router.include_router(api_graduation.make_router(config, gitea, bot))
+    # Slice 6: §15 notifications surface (inbox, watches, prefs,
+    # quiet hours, per-user mute, email unsubscribe, bounce webhook).
+    router.include_router(api_notifications.make_router(config))
 
     # ---------------------------------------------------------------
     # Auth surface — extends the prototype's pattern but reads role