- Add per-pad stop event system (_flash_stop_events dictionary)
- Add stop_flash(pad) method to cancel active flash animations
- flash_pad now checks stop events at multiple points in loop
- Tag removal handler calls stop_flash before setting pad to OFF
- Fixes issue where LED flash continued indefinitely after figure removed
- Tag detection turns ALL LEDs off immediately
- Server success shows CENTER blue blink (150ms)
- Theme effects (pulse/flash/solid) apply to ALL pads
- External tag_colors.json for customizable per-tag themes
- Debounce logic preserves theme effect even when skipping server
