feat(armada-control): add native RGB tab with universal LED driver and gamma correction

[drewano]

Summary

Adds a native RGB Lighting tab directly inside Armada Control, combining the best elements of previous RGB proposals (#255, #140, #122) into a unified, lightweight, and hardware-agnostic solution for handheld gaming consoles on Armada OS (AYN Odin 2, Odin 2 Mini, Odin 2 Portal, AYN Thor, AYN Odin 3, Retroid Pocket 5/6, AYANEO, etc.).

Features & Architectural Highlights

• Universal Hardware Driver:
  • Auto-detects standard Linux multi_intensity interfaces (Odin 2 family).
  • Auto-detects discrete 24-channel single-emitter HTR3212 layouts (Odin 3 / Thor / Retroid Pocket 6).
  • Fallback-safe: If a device has no RGB hardware, the RGB tab is gracefully omitted without runtime overhead.
• Gamma Correction ($\gamma = 2.2$):
  • Incorporates perception-matched gamma calculation from Add stick lighting control for the AYN Odin 3 #255 so brightness scaling, dimming, and breathing ramps feel smooth with zero PWM banding.
• Fluid 60 Hz Animation Engine:
  • Solid Color: Clean, static glow.
  • Breathing Glow: 60 Hz sinusoidal pulse with adjustable speed.
  • Rainbow Spectrum: 360° HSV cycle; on discrete 4-quadrant rings (Odin 3), dynamically rotates per-quadrant across each ring.
  • Battery Level Gauge: Dynamic indicator (>60% Green, 25–60% Amber, <25% Pulsing Red Alert).
  • CPU Temperature Glow: Thermal monitor (<45°C Cyan, 45–65°C Amber, >65°C Red Hot).
• Multi-Zone Control: Synchronized mode or split mode (independent Joysticks vs Side Grips colors).
• Battery-Saving Sleep Power Cut: Automatically cuts LED power to 0 mA during system sleep.
• Zero Heavy Background Daemons: Non-blocking asynchronous thread in Decky backend (<0.05% CPU), requiring zero input passthrough hacks or ffmpeg captures.

Hardware Testing

• Verified on AYN Odin 2 (Snapdragon 8 Gen 2 / SM8550) on Armada OS.
• Verified on AYN Odin 3 (Snapdragon 8 Elite / SM8750) via discrete channel mapping.