feat(lights): add universal color_off support for sirens, lights, and materials

[CanerKaraca23]

Summary

Adds universal support for custom \"color_off\" overrides across vehicle lights, sirens, and light materials via per-vehicle JSONC files.

Key Changes

• Universal Off-Color Resolution: Supports custom \"color_off\" hex values (#RRGGBB / #RRGGBBAA) in vehicle JSONC configurations for headlights, tail lights, indicators, fog lights, reverse lights, and sirens.
• Material Off State: Dynamically applies custom off-state colors to materials when lights/sirens are deactivated instead of defaulting to a single static dim color.
• API Exporters: Adds ME_GetLightColorOff support in ModelExtrasAPI.