docs: salvage focused stale PR contributions

- add Vite and Redis pattern skills from closed stale PRs

- add frontend-slides support assets

- port skill-comply runner fixes and LLM prompt/provider regressions

- harden agent frontmatter validation and sync catalog counts

tests/conftest.py

@@ -1,4 +1,10 @@
 import sys
 from pathlib import Path
 
+import pytest
+
 sys.path.insert(0, str(Path(__file__).parent.parent / "src"))
+
+
+def pytest_configure(config: pytest.Config) -> None:
+    config.addinivalue_line("markers", "unit: marks fast unit tests")