Add Mob KC Overlay plugin

[SubieSnack]

Mob KC Overlay is a simple kill-counter that tracks how many times you defeat any NPC you fight. It automatically detects which monster you are attacking (optional toggle) and saves separate kill counts for each NPC name. An on-screen overlay displays the current target and total kills, with an optional “+1” animation on each kill.

Features include:

• Automatic detection of the NPC you are attacking
• Manual selection by right-clicking any NPC → Show KC
• Saved kill counts per NPC
• Optional “+1” popup animation
• Custom text color, toggle options, and adjustable behavior
• Lightweight and fully client-side