M1: backend core + proposal engine

- FastAPI skeleton, SQLAlchemy models (§13), Alembic initial migration
- SchedulingProvider interface with google_calendar (free/busy read-only),
  partner_api (Appendix B client) and mock implementations
- Proposal engine: create → provider-routed delivery → owner actions
  (resolve/confirm+SMS/reject) → expiry + reminders (§9)
- Signed single-use action links, .ics METHOD:REQUEST attachment
- Partner outcome webhook with HMAC verification + polling fallback
- SmsProvider (console) with Bosnian templates (§5.5), EmailProvider (console/SMTP)
- Fake partner API server in tests/ — Appendix B reference implementation
- 43 tests: slot math, proposal lifecycle, action links, partner contract

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

gogo/main.py

@@ -0,0 +1,39 @@
+"""FastAPI application assembly."""
+
+from __future__ import annotations
+
+import logging
+from contextlib import asynccontextmanager
+
+from fastapi import FastAPI
+
+from gogo.api import actions, health, webhooks
+from gogo.config import get_settings
+
+logging.basicConfig(
+    level=logging.INFO, format="%(asctime)s %(levelname)s %(name)s %(message)s"
+)
+
+
+@asynccontextmanager
+async def lifespan(app: FastAPI):
+    scheduler = None
+    if get_settings().env != "test":
+        from gogo.jobs import build_scheduler
+
+        scheduler = build_scheduler()
+        scheduler.start()
+    yield
+    if scheduler:
+        scheduler.shutdown(wait=False)
+
+
+def create_app() -> FastAPI:
+    app = FastAPI(title="Gogo Telefon", docs_url=None, redoc_url=None, lifespan=lifespan)
+    app.include_router(health.router)
+    app.include_router(actions.router)
+    app.include_router(webhooks.router)
+    return app
+
+
+app = create_app()