refactor: key colors targets → CSS source type, HA target improvements

Key Colors refactor:
- New `key_colors` CSS source type with inline rectangles
- KeyColorsColorStripStream: extracts N colors from screen regions
- CSS editor: EntitySelect for picture source, IconSelect for color mode
- Configure Regions button on card opens pattern canvas editor
- Live WS preview at 5 FPS with rectangle overlay + color swatches
- Removed KC target type, pattern template entity, and related API routes
- Removed KC/pattern template sections from Targets tab

HA light target improvements:
- Update rate, transition, mappings, brightness VS now editable via PUT
- Card crosslinks for HA source, CSS source, brightness VS
- HA connection status icon, text metrics (Hz, uptime)
- Brightness value source selector in editor

server/src/wled_controller/api/__init__.py

@@ -9,10 +9,8 @@ from .routes.devices import router as devices_router
 from .routes.templates import router as templates_router
 from .routes.postprocessing import router as postprocessing_router
 from .routes.picture_sources import router as picture_sources_router
-from .routes.pattern_templates import router as pattern_templates_router
 from .routes.output_targets import router as output_targets_router
 from .routes.output_targets_control import router as output_targets_control_router
-from .routes.output_targets_keycolors import router as output_targets_keycolors_router
 from .routes.color_strip_sources import router as color_strip_sources_router
 from .routes.audio import router as audio_router
 from .routes.audio_sources import router as audio_sources_router
@@ -36,7 +34,6 @@ router.include_router(system_settings_router)
 router.include_router(devices_router)
 router.include_router(templates_router)
 router.include_router(postprocessing_router)
-router.include_router(pattern_templates_router)
 router.include_router(picture_sources_router)
 router.include_router(color_strip_sources_router)
 router.include_router(audio_router)
@@ -45,7 +42,6 @@ router.include_router(audio_templates_router)
 router.include_router(value_sources_router)
 router.include_router(output_targets_router)
 router.include_router(output_targets_control_router)
-router.include_router(output_targets_keycolors_router)
 router.include_router(automations_router)
 router.include_router(scene_presets_router)
 router.include_router(webhooks_router)