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/audio_sources.py

@@ -1,7 +1,6 @@
 """Audio source routes: CRUD for audio sources + real-time test WebSocket."""
 
 import asyncio
-import secrets
 from typing import Optional
 
 from fastapi import APIRouter, Depends, HTTPException, Query
@@ -21,7 +20,6 @@ from wled_controller.api.schemas.audio_sources import (
     AudioSourceResponse,
     AudioSourceUpdate,
 )
-from wled_controller.config import get_config
 from wled_controller.storage.audio_source import AudioSource
 from wled_controller.storage.audio_source_store import AudioSourceStore
 from wled_controller.storage.color_strip_store import ColorStripStore
@@ -169,16 +167,8 @@ async def test_audio_source_ws(
     (ref-counted — shares with running targets), and streams AudioAnalysis
     snapshots as JSON at ~20 Hz.
     """
-    # Authenticate
-    authenticated = False
-    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):
-                authenticated = True
-                break
-
-    if not authenticated:
+    from wled_controller.api.auth import verify_ws_token
+    if not verify_ws_token(token):
         await websocket.close(code=4001, reason="Unauthorized")
         return