fix: correct web API off endpoints and add blink task cancellation

Two issues fixed:

1. **Off endpoints not working**: The BusylightAPI.off() method was marked as
   async but called synchronous controller methods, causing await calls to fail.
   - Removed async from BusylightAPI.off() method
   - Removed await calls from off endpoints and startup/shutdown handlers

2. **Blink tasks not being canceled**: The turn_off() method only called
   light.off() but didn't cancel running tasks like blink effects.
   - Added light.cancel_tasks() before light.off() in turn_off() method
   - Added proper error handling for lights without task support

Fixed endpoints:
- GET /light/{light_id}/off - now properly turns off individual lights
- GET /lights/off - now properly turns off all lights
- Startup/shutdown handlers - now work without async issues

The off endpoints should now work and properly cancel any running blink tasks.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: JnyJny

src/busylight/api/busylight_api.py

@@ -96,7 +96,7 @@ def update(self) -> None:
     def release(self) -> None:
         self.controller.release_lights()
 
-    async def off(self, light_id: int = None) -> None:
+    def off(self, light_id: int = None) -> None:
         if light_id is None:
             self.controller.all().turn_off()
         else:
@@ -146,13 +146,13 @@ def authenticate_user(
 @busylightapi.on_event("startup")
 async def startup():
     busylightapi.update()
-    await busylightapi.off()
+    busylightapi.off()
 
 
 @busylightapi.on_event("shutdown")
 async def shutdown():
     try:
-        await busylightapi.off()
+        busylightapi.off()
     except Exception:
         logger.debug("problem during shutdown: {error}")
 
@@ -365,7 +365,7 @@ async def light_off(
     `color` can be a color name or a hexadecimal string e.g. "red",
     "#ff0000", "#f00", "0xff0000", "0xf00", "f00", "ff0000"
     """
-    await busylightapi.off(light_id)
+    busylightapi.off(light_id)
 
     return {
         "action": "off",
@@ -379,7 +379,7 @@ async def light_off(
 )
 async def lights_off() -> dict[str, Any]:
     """Turn off all lights."""
-    await busylightapi.off()
+    busylightapi.off()
 
     return {
         "action": "off",

src/busylight/controller.py

@@ -45,9 +45,14 @@ def turn_off(self) -> LightSelection:
         """Turn off selected lights."""
         for light in self.lights:
             try:
+                # Cancel any running tasks (like blink) before turning off
+                light.cancel_tasks()
                 light.off()
             except LightUnavailableError as error:
                 logger.debug(f"Light unavailable during turn_off: {error}")
+            except AttributeError:
+                # Light doesn't support task cancellation, just turn off
+                light.off()
         return self
 
     def blink(