Zombies: organic approach, honest eaten radius; restore CPU strength

- Personal lane offset (homeOff ±0.8m) + a per-zombie shamble wobble so
  on your half they fan around you instead of stacking into one column.
- Eaten check weights depth by 0.75 (z is foreshortened in the projection),
  so a head-on shambler kills you when it LOOKS on top of you — fixes
  "they touch me and I don't die." Lateral reach unchanged.
- Revert aiFlub 0.14 -> 0.09 (undo the CPU weakening).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

config.js

@@ -14,7 +14,7 @@ export const TUNE = {
   serveSpeed: 21, serveQualitySpeed: 7,
   aimError: 2.4,           // m of scatter at quality 0
   perfectMs: 45,           // |offset from window center| for PERFECT
-  aiQualityMin: 0.45, aiQualityMax: 0.85, aiFlub: 0.14, // ~86% of returns land (was 0.09) — a touch easier to beat
+  aiQualityMin: 0.45, aiQualityMax: 0.85, aiFlub: 0.09,
   aiReaction: 0.45,        // s before the CPU reads your shot — well-aimed corners are winners
   autoAssist: matchMedia('(pointer: coarse)').matches ? 1.15 : 0, // auto-run speed factor (mobile)
   zSpeed: 0.7,      // zombie shamble speed m/s