Kenzi's Buff Tracker

Optimizations:

• OnUpdate now throttled to 10 fps (0.1s interval) instead of running UpdateBuffs on every single frame — biggest performance win.
• UNIT_AURA still calls UpdateBuffs immediately and resets the throttle timer so buff changes feel instant.
• FontString outline is set once at creation time, not on every update tick.
• Single GetTime() call per update cycle; timeLeft now uses the cached currentTime.
• ApplyLockState() extracted to eliminate the duplicated lock texture/mouse logic.
• KenzisBuffTrackerDB = KenzisBuffTrackerDB or { isLocked = false } replaces the nil-check block.
• Simplified timed-buff color branching: timeLeft < 120 → red is checked once for both world and normal buffs, then gold vs. white is resolved in the elseif.