Gat Modular UI

New Features:

• Tools: Enemy Cast Bars - Shows cast bars when enemy nameplate units are casting spells. Uses M+ combat-safe engine APIs (UnitCastingDuration, SetTimerDuration, SetVertexColorFromBoolean) — no manual arithmetic on secret values. Interruptible/non-interruptible color coding, spell icon and name, countdown timer, class-colored target name, optional caster name. Pool-based bar management, environment gating (5-player dungeons by default, configurable for party/everywhere), preview mode (/gecb test), EditMode positioning, and full customization options (bar size, colors, fonts, texture, scale). Accessible via /gecb slash command and the Enemy Cast Bars tab in /gtools