feat(processed-audio-sources): phase 7 - testing and polish

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.

server/src/wled_controller/api/routes/audio_processing_templates.py

@@ -134,8 +134,8 @@ async def update_audio_processing_template(
         try:
             pm = get_processor_manager()
             pm.refresh_audio_filter_pipelines(template_id)
-        except Exception:
-            pass  # Non-critical: streams will pick up changes on next restart
+        except Exception as exc:
+            logger.warning("Hot-update of audio filter pipelines failed: %s", exc)
         return _apt_to_response(template)
     except EntityNotFoundError as e:
         raise HTTPException(status_code=404, detail=str(e))
@@ -158,15 +158,14 @@ async def delete_audio_processing_template(
 ):
     """Delete an audio processing template."""
     try:
-        # TODO: Phase 3 will add reference checks against ProcessedAudioSource
         store.delete_template(template_id)
         fire_entity_event("audio_processing_template", "deleted", template_id)
         # Hot-update: rebuild filter pipelines for running streams that used this template
         try:
             pm = get_processor_manager()
             pm.refresh_audio_filter_pipelines(template_id)
-        except Exception:
-            pass  # Non-critical
+        except Exception as exc:
+            logger.warning("Hot-update of audio filter pipelines after delete failed: %s", exc)
     except HTTPException:
         raise
     except EntityNotFoundError as e: