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>