Initial KDS scaffold — Phase 2 kitchen port

FastAPI backend (Python 3.11, httpx for SignalR/GraphQL — no MSSQL ODBC),
shares kitchen_db directly. React/TS/Vite fullscreen board frontend.

Backend: auth.py (APP_SLUG=kds, SimpleNamespace), main.py (4 KDS migrations,
SignalR start/stop), kds.py router, models (kds/settings/resos — read from
kitchen_db), signalr_listener.py (backoff pre-existing), kds_graphql.py,
database.py. Requirements stripped to ~9 packages; image ~400 MB lighter
than kitchen (no MSSQL ODBC layer).

Frontend: AuthGate (app=kds), single fullscreen route, dark board theme.
KDS.tsx URL prefix patched (/api/kds/ → /kds/api/kds/),
recipe images cross-app (/kitchen/api/recipes/).
nginx: 5 blocks with SSE proxy headers on /kds/api/ block.

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

backend/migrations/add_kds_bookings_refresh.py

@@ -0,0 +1,38 @@
+"""
+Migration: Add KDS bookings refresh interval setting.
+
+Adds:
+- kds_bookings_refresh_seconds column to kitchen_settings
+"""
+
+import asyncio
+import logging
+from sqlalchemy import text
+from database import engine
+
+logger = logging.getLogger(__name__)
+
+
+async def run_migration():
+    """Add KDS bookings refresh interval column."""
+
+    alter_statements = [
+        """
+        ALTER TABLE kitchen_settings
+        ADD COLUMN IF NOT EXISTS kds_bookings_refresh_seconds INTEGER DEFAULT 60
+        """,
+    ]
+
+    try:
+        async with engine.begin() as conn:
+            for sql in alter_statements:
+                await conn.execute(text(sql))
+            logger.info("Added KDS bookings refresh interval column")
+    except Exception as e:
+        if "already exists" not in str(e).lower():
+            raise
+        logger.warning(f"KDS bookings refresh migration: {e}")
+
+
+if __name__ == "__main__":
+    asyncio.run(run_migration())