feat(connect): Phase 3 — cloud API routes for Xenia Connect

Adds four new routers, three schema files, and one new model.
All new endpoints use new URL prefixes — no existing routes touched.

routers/menu.py
  GET  /api/menu/{site_slug}     — public menu snapshot (no auth)
  POST /api/menu/sync            — upsert snapshot (site API key)

routers/orders.py
  POST /api/orders/{site_slug}         — customer places order (public)
  GET  /api/orders/status/{public_ref} — customer tracks order (public)
  GET  /api/orders/pending/{site_id}   — local backend polls (site key)
  POST /api/orders/{id}/synced         — mark synced (site key)
  PATCH /api/orders/{id}/status        — update status with transition
                                         validation (site key)

routers/manager_auth.py
  POST /api/manager/register  — create manager account (admin JWT)
  POST /api/manager/login     — returns manager JWT
  POST /api/manager/refresh   — refreshes manager JWT
  Shared _get_current_manager dependency used by remote_dashboard

routers/remote_dashboard.py
  GET  /api/remote/sites                           — manager JWT
  GET  /api/remote/sites/{id}/snapshot             — manager JWT
  GET  /api/remote/sites/{id}/orders               — manager JWT
  GET  /api/remote/sites/{id}/orders/pending       — manager JWT
  PATCH /api/remote/sites/{id}/orders/{oid}/status — manager JWT
  POST /api/remote/snapshot                        — site API key
                                                     (stats push)

models/stats_snapshot.py (NEW)
  stats_snapshots table — one row per site, holds serialized
  operational stats; created by create_all on startup

config.py / .env.example
  MANAGER_JWT_SECRET and MANAGER_JWT_EXPIRE_HOURS (default 72h)
  added as separate settings from the admin SECRET_KEY

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cloud_backend/config.py

@@ -11,6 +11,9 @@ class Settings(BaseSettings):
     ADMIN_USERNAME: str = "sysadmin"
     ADMIN_PASSWORD: str = "changeme"
     LATEST_VERSION: str = "0.0.0"
+    # Manager JWT (separate secret from admin JWT)
+    MANAGER_JWT_SECRET: str = "change-me-manager-secret"
+    MANAGER_JWT_EXPIRE_HOURS: int = 72
 
     model_config = {"env_file": str(_HERE / ".env")}