ac-power enhancements:
- Add visual block gauge [████░░░░] colored by power level
- Show delta indicator (+50W) colored by trend (green=dropping, red=rising)
- Track min/max values with persistence to ~/.cache/mpv/
- Multi-process safe file writes (merges values on save)
- New script-message: ac-power-reset-minmax
Shared library (scripts/lib/utils.lua):
- Extract common helpers: trim, clamp, rgb_to_bgr, colorize
- Update all scripts to use shared module via package.path
- playback-health: skip bandwidth warning when buffer is healthy
(configurable via bandwidth_buffer_mult, default 10× warning threshold)
- touch-gestures: use finer steps at low volume/brightness (<10%)
(configurable via volume_step_fine, brightness_step_fine, fine_threshold)
