Add CSPT entity, processed CSS source type, reverse filter, and UI improvements

- Add Color Strip Processing Template (CSPT) entity: reusable filter chains
  for 1D LED strip postprocessing (backend, storage, API, frontend CRUD)
- Add "processed" color strip source type that wraps another CSS source and
  applies a CSPT filter chain (dataclass, stream, schema, modal, cards)
- Add Reverse filter for strip LED order reversal
- Add CSPT and processed CSS nodes/edges to visual graph editor
- Add CSPT test preview WS endpoint with input source selection
- Add device settings CSPT template selector (add + edit modals with hints)
- Use icon grids for palette quantization preset selector in filter lists
- Use EntitySelect for template references and test modal source selectors
- Fix filters.css_filter_template.desc missing localization
- Fix icon grid cell height inequality (grid-auto-rows: 1fr)
- Rename "Processed" subtab to "Processing Templates"
- Localize all new strings (en/ru/zh)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

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

@@ -26,13 +26,12 @@ PREVIEW_JPEG_QUALITY = 70
 
 
 def authenticate_ws_token(token: str) -> bool:
-    """Check a WebSocket query-param token against configured API keys."""
-    cfg = get_config()
-    if token and cfg.auth.api_keys:
-        for _label, api_key in cfg.auth.api_keys.items():
-            if secrets.compare_digest(token, api_key):
-                return True
-    return False
+    """Check a WebSocket query-param token against configured API keys.
+
+    Delegates to the canonical implementation in auth module.
+    """
+    from wled_controller.api.auth import verify_ws_token
+    return verify_ws_token(token)
 
 
 def _encode_jpeg(pil_image: Image.Image, quality: int = 85) -> str: