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/Dockerfile

@@ -0,0 +1,19 @@
+FROM python:3.11-slim
+
+ENV PYTHONDONTWRITEBYTECODE=1
+ENV PYTHONUNBUFFERED=1
+
+RUN apt-get update && apt-get install -y --no-install-recommends curl \
+    && rm -rf /var/lib/apt/lists/*
+
+WORKDIR /app
+
+COPY requirements.txt .
+RUN pip install --no-cache-dir --upgrade pip && \
+    pip install --no-cache-dir -r requirements.txt
+
+COPY . .
+
+EXPOSE 8000
+
+CMD ["uvicorn", "main:app", "--host", "0.0.0.0", "--port", "8000"]