Trap Manager 1.4.2 (compat package)

Changes made for broader Build 42 compatibility:
- Added mandatory common/ folder and split versioned branches: 42.12 and 42.15.
- Shared Lua, translations and UI assets now live in common/media.
- 42.12 branch is intended for 42.12.x and 42.13.x.
- 42.15 branch is intended for 42.15.x and later 42.15+ builds until another API change happens.
- Hardened Lua load order by explicitly requiring UI files used by the mod.
- Trap system selection now prefers CTrapSystem when available and falls back to STrapSystem.
- Updated 42.15 mod.info require syntax to the post-42.15 ModID format.
