fix(spicetify): refresh playback colors on theme changes

[yukazakiri]

Summary

Fixes Spicetify theme regeneration so playback controls update consistently when the wallpaper palette changes.

Motivation

The generated user.css could accumulate malformed duplicate playback override blocks, which left stale playback control colors behind after theme changes. This rewrites the bridge and playback fix blocks deterministically on each run so only the current palette is applied.

Testing

Steps to verify this works:

1. Run bash -n scripts/colors/apply-spicetify-theme.sh to verify the script syntax.
2. Run scripts/colors/apply-spicetify-theme.sh and inspect ~/.config/spicetify/Themes/Inir/user.css to confirm there is exactly one playback controls block and one bridge block.
3. Change the wallpaper or theme again and confirm the playback controls update from the latest palette without leaving duplicate stale CSS blocks.

Checklist

• Tested on Niri (or Hyprland if applicable)
• Tested both ii and waffle families for UI changes
• Tested material, aurora, and inir styles for ii changes
• No hardcoded values (colors, fonts, durations use design tokens)
• Config changes synced in Config.qml and defaults/config.json
• Config access uses optional chaining: Config.options?.section?.option ?? default
• IPC functions have explicit return types (: void, : string, etc.)
• Shell restarted after changes: inir restart
• Logs checked for errors: inir logs
• Lazy-loaded components tested (Settings, overlays)
• No console errors or warnings

Related

Closes #
Fixes #