Better Mob Combat Fix [BMCFIX]

# Better Mob Combat Fix Fixes Better Mob Combat compatibility with Better Combat 1.9.0 ## The Problem Better Combat 1.9.0 (latest for 1.20.1) made breaking changes: 1. Removed `CompatibilityFlags.firstPersonRender()` method 2. Moved `PehkuiHelper` from `net.bettercombat.compatibility` to `net.bettercombat.client.compat` Better Mob Combat stopped updating and still uses old methods/paths, breaking mob attack animations and Pehkui compatibility. ## How It Works This mod uses two mixins to fix both issues: **Mixin 1:** Intercepts `CompatibilityFlags.firstPersonRender()` calls and returns `false` **Mixin 2:** Overwrites `BMCPehkuiHelper.load()` to use the new PehkuiHelper location **Technical:** - `@Redirect` on `Mob.playAttackAnimation()` → returns `false` for removed method - `@Overwrite` on `BMCPehkuiHelper.load()` → uses `net.bettercombat.client.compat.PehkuiHelper`