Unify process picker, improve notification CSS editor, remove notification led_count

- Extract shared process picker module (core/process-picker.js) used by
  both automation conditions and notification CSS app filter
- Remove led_count property from notification CSS source (backend + frontend)
- Replace comma-separated app filter with newline-separated textarea + browse
- Inline color cycle add button (+) into the color row
- Fix notification app color layout to horizontal rows

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/wled_controller/storage/color_strip_source.py

@@ -238,7 +238,6 @@ class ColorStripSource:
                 app_filter_mode=data.get("app_filter_mode") or "off",
                 app_filter_list=app_filter_list,
                 os_listener=bool(data.get("os_listener", False)),
-                led_count=data.get("led_count") or 0,
             )
 
         # Default: "picture" type
@@ -504,7 +503,6 @@ class NotificationColorStripSource(ColorStripSource):
     app_filter_mode: str = "off"             # off | whitelist | blacklist
     app_filter_list: list = field(default_factory=list)  # app names for filter
     os_listener: bool = False                # whether to listen for OS notifications
-    led_count: int = 0                       # 0 = use device LED count
 
     def to_dict(self) -> dict:
         d = super().to_dict()
@@ -515,5 +513,4 @@ class NotificationColorStripSource(ColorStripSource):
         d["app_filter_mode"] = self.app_filter_mode
         d["app_filter_list"] = list(self.app_filter_list)
         d["os_listener"] = self.os_listener
-        d["led_count"] = self.led_count
         return d

server/src/wled_controller/storage/color_strip_store.py

@@ -279,7 +279,6 @@ class ColorStripStore:
                 app_filter_mode=app_filter_mode or "off",
                 app_filter_list=app_filter_list if isinstance(app_filter_list, list) else [],
                 os_listener=bool(os_listener) if os_listener is not None else False,
-                led_count=led_count,
             )
         else:
             if calibration is None:
@@ -472,8 +471,6 @@ class ColorStripStore:
                 source.app_filter_list = app_filter_list
             if os_listener is not None:
                 source.os_listener = bool(os_listener)
-            if led_count is not None:
-                source.led_count = led_count
 
         source.updated_at = datetime.utcnow()
         self._save()