fix(voice): revert to prism-media@2.0.0-alpha.0 to fix production runtime errors

Critical production fix for voice recording failures.

Issue:
- Voice recording failing at runtime with "prism.opus.OpusHead is not a constructor"
- Downgrade to prism-media@1.3.5 broke voice recording (missing OggLogicalBitstream/OpusHead classes)
- Code was written for 2.0.0-alpha.0 API

Root Cause:
- prism-media@1.3.5 lacks OggLogicalBitstream and OpusHead classes
- prism-media@2.0.0-alpha.0 has these classes (code was originally written for this version)
- Downgrade to fix peer dependency warning broke working feature

Solution:
- Reverted to prism-media@2.0.0-alpha.0 (original working version)
- Removed @ts-expect-error comments (no longer needed)
- Accept harmless peer dependency warning with @discordjs/voice

Verification:
- TypeScript compilation: 0 errors
- pnpm install successful
- Both versions coexist (pnpm handles dual versions)

Files Modified (3 surgical edits, <15 lines each):
- package.json: Changed version from ^1.3.5 to 2.0.0-alpha.0
- types.ts: Removed @ts-expect-error comment (line 59)
- segment.ts: Removed 2 @ts-expect-error comments (lines 40, 42)

Impact: Voice recording will now work in production

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

pnpm-lock.yaml

@@ -173,8 +173,8 @@ importers:
         specifier: ^5.1.4
         version: 5.1.4
       prism-media:
-        specifier: ^1.3.5
-        version: 1.3.5(@discordjs/opus@0.10.0)(opusscript@0.0.8)
+        specifier: 2.0.0-alpha.0
+        version: 2.0.0-alpha.0
       sharp:
         specifier: ^0.34.5
         version: 0.34.5