Sync LED colour with the current theme's primary colour

[lepht]

The LEDs are configured independently of the UI theme today, so changing a colour palette leaves them on whatever they were set to. They should be able to follow the theme.

What exists

• LightSettings (api.h) carries color1 / color2 per light, with PLAT_setLedColor() / PLAT_setLedEffect() behind it and LEDS_applyRules() in api.c deciding what's active
• The LedControl pak (workspace/all/ledcontrol/) is the UI for setting them
• Theme primary is CFG_getColor(COLOR_MAIN) / THEME_COLOR1_255, and palettes swap it wholesale via CFG_applyPalette()

Proposal

A per-light "follow theme" option that drives color1 (and optionally color2 from the accent) off the theme rather than a stored value.

The hook already exists: NextUISettings has a ColorSet_callback_t onColorSet invoked when colours change. Wiring LED re-application into that gets palette switches and individual colour edits for free, without polling.

Notes

• MAX_LIGHTS is 0 on platforms without LEDs — has to compile out cleanly
• Respect the existing muteLeds setting; "follow theme" shouldn't override a mute
• Theme colours are stored unmapped as 0xRRGGBBAA while some LED paths expect screen-mapped values — check which the LED code wants before assuming
• Worth deciding whether this applies to the ambient/effect modes or only static colour