feat: add web UI, query engine, session management, and 20 E2E tests

- Web UI: login, dashboard, links CRUD, collections, API keys, admin pages
- Query engine: AND/OR/XOR with field filters, tag search, preview endpoint
- Session management: token expiry detection, 401 interceptor, expiry banner
- Links search: tags included, multi-word AND, query mode with set operations
- Collections: static/dynamic, query builder with preview, public tree view
- Save as Collection: convert search results (static) or query (dynamic)
- Dashboard stats: resilient loading with allSettled pattern
- Login page: redesigned with public collections tree view
- Bug fix: query executor None fields crash (notes/description/url/title)
- E2E tests: 20 Playwright tests covering all critical user flows
- All 104 tests passing (84 unit/integration + 20 E2E)

LinkSyncServer/pyproject.toml

@@ -39,6 +39,7 @@ python_files = ["test_*.py"]
 python_functions = ["test_*"]
 addopts = "-v --tb=short"
 filterwarnings = ["ignore::DeprecationWarning"]
+markers = ["e2e: End-to-end Playwright tests"]
 
 [tool.ruff]
 line-length = 88