test: add comprehensive test suite (Go unit/integration, Vitest, Playwright E2E)

- Add JWT middleware unit tests (8 tests covering all auth edge cases)
- Add WebSocket hub tests (5 tests for client lifecycle and broadcast)
- Add full HTTP integration tests (12 tests through real Chi router with DB)
- Add frontend component tests for login, issues, and issue detail pages
- Add auth context unit tests (9 tests for login/logout/name resolution)
- Add Playwright E2E tests for auth, issues, comments, and navigation
- Configure Vitest with jsdom, React plugin, and path aliases

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

package.json

@@ -22,6 +22,7 @@
     }
   },
   "devDependencies": {
+    "@playwright/test": "^1.58.2",
     "@types/node": "catalog:",
     "turbo": "^2.5.0",
     "typescript": "catalog:"