Pin @angular/build and @angular/cli to version 19.2.7

- Use specific version 19.2.7 for build tools instead of ^19.1.0
- Angular core packages remain at ^19.1.0
- This specific build version may have better package resolution
  for restricted/air-gapped environments

Using a pinned version ensures consistent builds across different
environments and may help with package availability issues.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

frontend/package.json

@@ -34,8 +34,8 @@
     "zone.js": "~0.15.0"
   },
   "devDependencies": {
-    "@angular/build": "^19.1.0",
-    "@angular/cli": "^19.1.0",
+    "@angular/build": "19.2.7",
+    "@angular/cli": "19.2.7",
     "@angular/compiler-cli": "^19.1.0",
     "@types/jasmine": "~5.1.0",
     "jasmine-core": "~5.9.0",