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/dependencies.py

@@ -11,7 +11,6 @@ from wled_controller.storage.database import Database
 from wled_controller.storage import DeviceStore
 from wled_controller.storage.template_store import TemplateStore
 from wled_controller.storage.postprocessing_template_store import PostprocessingTemplateStore
-from wled_controller.storage.pattern_template_store import PatternTemplateStore
 from wled_controller.storage.picture_source_store import PictureSourceStore
 from wled_controller.storage.output_target_store import OutputTargetStore
 from wled_controller.storage.color_strip_store import ColorStripStore
@@ -64,10 +63,6 @@ def get_pp_template_store() -> PostprocessingTemplateStore:
     return _get("pp_template_store", "Postprocessing template store")
 
 
-def get_pattern_template_store() -> PatternTemplateStore:
-    return _get("pattern_template_store", "Pattern template store")
-
-
 def get_picture_source_store() -> PictureSourceStore:
     return _get("picture_source_store", "Picture source store")
 
@@ -188,7 +183,6 @@ def init_dependencies(
     processor_manager: ProcessorManager,
     database: Database | None = None,
     pp_template_store: PostprocessingTemplateStore | None = None,
-    pattern_template_store: PatternTemplateStore | None = None,
     picture_source_store: PictureSourceStore | None = None,
     output_target_store: OutputTargetStore | None = None,
     color_strip_store: ColorStripStore | None = None,
@@ -218,7 +212,6 @@ def init_dependencies(
             "template_store": template_store,
             "processor_manager": processor_manager,
             "pp_template_store": pp_template_store,
-            "pattern_template_store": pattern_template_store,
             "picture_source_store": picture_source_store,
             "output_target_store": output_target_store,
             "color_strip_store": color_strip_store,