Add Docker cache buster to force rebuild

- Add ARG CACHE_BUST to force rebuild of code layer
- Ensures latest mcp_auth_http_simple.py syntax fix is deployed
- Resolves JSON syntax error in OAuth metadata endpoint

Forces fresh container build without cache

Dockerfile

@@ -11,6 +11,10 @@ COPY pyproject.toml poetry.lock* requirements*.txt* ./
 RUN pip install --no-cache-dir uv && \
     uv pip install --system --no-cache-dir .[asgi,saas]
 
+# Cache buster - force rebuild
+ARG CACHE_BUST=202507221015
+RUN echo "Cache bust: $CACHE_BUST"
+
 # Copy application source
 COPY . .