feat: add system tray and __main__ entry point

Add pystray-based system tray icon with Open UI / Restart / Quit
actions. Add __main__.py for `python -m wled_controller` support.
Update start-hidden.vbs with embedded Python fallback for both
installed and dev environments.

server/src/wled_controller/main.py

@@ -32,6 +32,7 @@ from wled_controller.storage.automation_store import AutomationStore
 from wled_controller.storage.scene_preset_store import ScenePresetStore
 from wled_controller.storage.sync_clock_store import SyncClockStore
 from wled_controller.storage.color_strip_processing_template_store import ColorStripProcessingTemplateStore
+from wled_controller.storage.gradient_store import GradientStore
 from wled_controller.core.processing.sync_clock_manager import SyncClockManager
 from wled_controller.core.automations.automation_engine import AutomationEngine
 from wled_controller.core.mqtt.mqtt_service import MQTTService
@@ -69,6 +70,8 @@ automation_store = AutomationStore(config.storage.automations_file)
 scene_preset_store = ScenePresetStore(config.storage.scene_presets_file)
 sync_clock_store = SyncClockStore(config.storage.sync_clocks_file)
 cspt_store = ColorStripProcessingTemplateStore(config.storage.color_strip_processing_templates_file)
+gradient_store = GradientStore(config.storage.gradients_file)
+gradient_store.migrate_palette_references(color_strip_store)
 sync_clock_manager = SyncClockManager(sync_clock_store)
 
 processor_manager = ProcessorManager(
@@ -84,6 +87,7 @@ processor_manager = ProcessorManager(
         audio_template_store=audio_template_store,
         sync_clock_manager=sync_clock_manager,
         cspt_store=cspt_store,
+        gradient_store=gradient_store,
     )
 )
 
@@ -167,6 +171,7 @@ async def lifespan(app: FastAPI):
         sync_clock_store=sync_clock_store,
         sync_clock_manager=sync_clock_manager,
         cspt_store=cspt_store,
+        gradient_store=gradient_store,
     )
 
     # Register devices in processor manager for health monitoring