CUB-66: scaffold Angular frontend and add Dockerfile with nginx

- Scaffolded Angular 21 app in frontend/ (standalone, routing, scss)
- Multi-stage Dockerfile: node:22-alpine build → nginx:alpine serve
- nginx.conf with SPA routing fallback, API proxy, gzip, asset caching
- .dockerignore excludes node_modules, dist, .angular, spec files
- docker build → PASS, container serves UI on port 80 (HTTP 200)
- Final image: 92.9MB (nginx:alpine)

frontend/.vscode/mcp.json

@@ -0,0 +1,9 @@
+{
+  // For more information, visit: https://angular.dev/ai/mcp
+  "servers": {
+    "angular-cli": {
+      "command": "npx",
+      "args": ["-y", "@angular/cli", "mcp"]
+    }
+  }
+}