The /filaments/ endpoint manages material type definitions (cost, temps,
density) but shares its name with the UI's "Filament" page which shows
the spool inventory (/inventory/spools/). This caused users to expect
the API to return their spool inventory.
Rename to /filament-catalog/ to make the distinction clear. No frontend
behavior change — these API methods are defined but unused in the UI.
- Remove 28 unused imports across 22 test files
- Prefix 4 unused local variables with _ in app code
(archives, bambu_mqtt, main) and remove 1 dead store
- Consolidate import/import-from in test_plate_detection.py
- Fix unreachable statement in test_archive_service.py
- Simplify redundant comparison in timelapse_processor.py
Resolves ~50 CodeQL py/unused-import, py/unused-local-variable,
py/import-and-import-from, py/unreachable-statement, and
py/redundant-comparison findings.