Upgrade local web gateway with structured YouTube support

platform/mcp/Dockerfile.web

@@ -1,7 +1,11 @@
 FROM python:3.13-slim
 
 ARG MCP_PROXY_VERSION=0.12.0
-RUN pip install --no-cache-dir "mcp-proxy==${MCP_PROXY_VERSION}" "mcp>=1.17,<2"
+ARG YT_DLP_VERSION=2026.7.4
+RUN pip install --no-cache-dir \
+    "mcp-proxy==${MCP_PROXY_VERSION}" \
+    "mcp>=1.17,<2" \
+    "yt-dlp==${YT_DLP_VERSION}"
 
 RUN useradd --system --uid 10001 --create-home --home-dir /app mcp
 COPY web-search/web_search_mcp.py /app/web_search_mcp.py