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/__init__.py

@@ -18,6 +18,7 @@ from .routes.automations import router as automations_router
 from .routes.scene_presets import router as scene_presets_router
 from .routes.webhooks import router as webhooks_router
 from .routes.sync_clocks import router as sync_clocks_router
+from .routes.color_strip_processing import router as cspt_router
 
 router = APIRouter()
 router.include_router(system_router)
@@ -36,5 +37,6 @@ router.include_router(automations_router)
 router.include_router(scene_presets_router)
 router.include_router(webhooks_router)
 router.include_router(sync_clocks_router)
+router.include_router(cspt_router)
 
 __all__ = ["router"]