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/utils/gpu.py

@@ -0,0 +1,24 @@
+"""GPU monitoring state (NVIDIA via pynvml).
+
+Extracted from system routes so core modules can access GPU metrics
+without importing from the API layer.
+"""
+
+from wled_controller.utils import get_logger
+
+logger = get_logger(__name__)
+
+nvml_available = False
+nvml = None
+nvml_handle = None
+
+try:
+    import pynvml as _pynvml_mod
+
+    _pynvml_mod.nvmlInit()
+    nvml_handle = _pynvml_mod.nvmlDeviceGetHandleByIndex(0)
+    nvml_available = True
+    nvml = _pynvml_mod
+    logger.info(f"NVIDIA GPU monitoring enabled: {nvml.nvmlDeviceGetName(nvml_handle)}")
+except Exception:
+    logger.info("NVIDIA GPU monitoring unavailable (pynvml not installed or no NVIDIA GPU)")