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>

docker-compose.yml

@@ -0,0 +1,38 @@
+services:
+  db:
+    image: postgres:16-alpine
+    environment:
+      POSTGRES_USER: gogo
+      POSTGRES_PASSWORD: gogo
+      POSTGRES_DB: gogo
+    ports:
+      - "127.0.0.1:5433:5432"  # 5433 on the host to avoid clashing with a system postgres
+    volumes:
+      - pgdata:/var/lib/postgresql/data
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U gogo"]
+      interval: 5s
+      timeout: 3s
+      retries: 10
+
+  app:
+    build: .
+    depends_on:
+      db:
+        condition: service_healthy
+    environment:
+      GOGO_DATABASE_URL: postgresql+psycopg://gogo:gogo@db:5432/gogo
+    env_file:
+      - path: .env
+        required: false
+    ports:
+      - "127.0.0.1:8000:8000"
+    volumes:
+      - recordings:/data/recordings
+    command: >
+      sh -c "alembic upgrade head &&
+             uvicorn gogo.main:app --host 0.0.0.0 --port 8000"
+
+volumes:
+  pgdata:
+  recordings: