Move FPS from color strip source to target; dynamic capture rate

FPS is a consumption property (how fast to send to a device), not a
production property. Two targets sharing the same source may need
different FPS. This moves the fps field from PictureColorStripSource
to WledPictureTarget across the full stack.

The capture stream now auto-adjusts its rate to max(all connected
target FPS values) via ColorStripStreamManager tracking per-consumer
FPS. UI updates: FPS slider in target editor, FPS badge on target
cards, LED count repositioned in CSS editor, consistent speed icons.

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

server/src/wled_controller/api/routes/picture_targets.py

@@ -94,6 +94,7 @@ def _target_to_response(target) -> PictureTargetResponse:
             target_type=target.target_type,
             device_id=target.device_id,
             color_strip_source_id=target.color_strip_source_id,
+            fps=target.fps,
             standby_interval=target.standby_interval,
             state_check_interval=target.state_check_interval,
             description=target.description,
@@ -148,6 +149,7 @@ async def create_target(
             target_type=data.target_type,
             device_id=data.device_id,
             color_strip_source_id=data.color_strip_source_id,
+            fps=data.fps,
             standby_interval=data.standby_interval,
             state_check_interval=data.state_check_interval,
             picture_source_id=data.picture_source_id,
@@ -243,6 +245,7 @@ async def update_target(
             name=data.name,
             device_id=data.device_id,
             color_strip_source_id=data.color_strip_source_id,
+            fps=data.fps,
             standby_interval=data.standby_interval,
             state_check_interval=data.state_check_interval,
             picture_source_id=data.picture_source_id,
@@ -254,7 +257,8 @@ async def update_target(
         try:
             target.sync_with_manager(
                 manager,
-                settings_changed=(data.standby_interval is not None or
+                settings_changed=(data.fps is not None or
+                                  data.standby_interval is not None or
                                   data.state_check_interval is not None or
                                   data.key_colors_settings is not None),
                 source_changed=data.color_strip_source_id is not None,