Tests that imported wled_controller.main at module level caused the real
production database (data/ledgrab.db) to be opened before test fixtures
could patch the config. This led to silent data loss.
Patch the global config singleton at conftest module level (before any
test imports main.py) to redirect all DB access to a temp directory.
Fix test_list_filters test (filter_id field name mismatch).
Add tests for audio filters, template store, and source store.
All 678 tests pass, ruff clean, tsc clean, esbuild clean.
No dead code remaining from old source types.
alexei.dolgolyov