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/templates.py

@@ -11,6 +11,7 @@ from fastapi import APIRouter, HTTPException, Depends, Query, WebSocket, WebSock
 from wled_controller.api.auth import AuthRequired
 from wled_controller.api.dependencies import (
     fire_entity_event,
+    get_cspt_store,
     get_picture_source_store,
     get_pp_template_store,
     get_template_store,
@@ -479,3 +480,48 @@ async def list_filter_types(
             options_schema=opt_schemas,
         ))
     return FilterTypeListResponse(filters=responses, count=len(responses))
+
+
+@router.get("/api/v1/strip-filters", response_model=FilterTypeListResponse, tags=["Filters"])
+async def list_strip_filter_types(
+    _auth: AuthRequired,
+    cspt_store=Depends(get_cspt_store),
+):
+    """List filter types that support 1D LED strip processing."""
+    all_filters = FilterRegistry.get_all()
+
+    # Pre-build template choices for the css_filter_template filter
+    cspt_choices = None
+    if cspt_store:
+        try:
+            templates = cspt_store.get_all_templates()
+            cspt_choices = [{"value": t.id, "label": t.name} for t in templates]
+        except Exception:
+            cspt_choices = []
+
+    responses = []
+    for filter_id, filter_cls in all_filters.items():
+        if not getattr(filter_cls, "supports_strip", True):
+            continue
+        schema = filter_cls.get_options_schema()
+        opt_schemas = []
+        for opt in schema:
+            choices = opt.choices
+            if filter_id == "css_filter_template" and opt.key == "template_id" and cspt_choices is not None:
+                choices = cspt_choices
+            opt_schemas.append(FilterOptionDefSchema(
+                key=opt.key,
+                label=opt.label,
+                type=opt.option_type,
+                default=opt.default,
+                min_value=opt.min_value,
+                max_value=opt.max_value,
+                step=opt.step,
+                choices=choices,
+            ))
+        responses.append(FilterTypeResponse(
+            filter_id=filter_cls.filter_id,
+            filter_name=filter_cls.filter_name,
+            options_schema=opt_schemas,
+        ))
+    return FilterTypeListResponse(filters=responses, count=len(responses))