feat(api): add MCP server for scan management

Add a Model Context Protocol server to apps/api/src/mcp/, exposing
five tools backed by scan-manager.ts:
- start_scan, get_scan, list_scans, cancel_scan, get_report

The MCP server runs on port 3100 (MCP_PORT env var) using
StreamableHTTPServerTransport from @modelcontextprotocol/sdk, alongside
the existing Hono API server.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/api/package.json

@@ -12,6 +12,7 @@
   "dependencies": {
     "@hono/node-server": "^1.14.0",
     "@kubernetes/client-node": "^1.4.0",
+    "@modelcontextprotocol/sdk": "^1.29.0",
     "@shannon/worker": "workspace:*",
     "@temporalio/client": "^1.11.0",
     "hono": "^4.7.0",