v1.10 — Main Board rainbow no longer leaves keys grey

Fixes reported directly from live use:

• Main Board's Rainbow preset used to skip the six keys with no individual LED (Win/Alt/AltGr/Menu/right-Ctrl/right-Shift), leaving them visibly grey. It now fills them with the gradient's starting hue via a whole-block fill, same mechanism the static colour apply already used.
• Rainbow now picks a random starting hue every click instead of the same fixed gradient each time.
• Breathing/Colour Cycle/Rainbow Wave/Speed moved out of the main Color Mode panel into a separate Effects (WIP) tab — marked work-in-progress because the on-screen preview for a few keys can still lag the real keyboard during an animation. Switching zones or tabs now stops any running effect automatically, and there's a dedicated Stop Effects button.
• Fixed a stale v1.8 download-link example left over in INSTALL.md.

Verified: namcap-clean (same two known false positives as every prior release), extracted-package personal-data audit clean, headless launch of the actual built package with no keyboard simulated, and the rainbow fill tested live against real hardware.