Modernize Discord bot to v14 and Node.js 22

Major upgrades and architectural improvements:
- Upgrade Discord.js from v12 to v14.21.0
- Upgrade Node.js from 14 to 22 LTS
- Switch to pnpm package manager
- Complete rewrite with modern Discord API patterns

New Features:
- Hybrid command system: prefix commands + slash commands
- /sfx slash command with autocomplete for sound discovery
- Modern @discordjs/voice integration for audio
- Improved voice connection management
- Enhanced logging for SFX commands
- Multi-stage Docker build for optimized images

Technical Improvements:
- Modular architecture with services and command handlers
- Proper intent management for Discord gateway
- Better error handling and logging
- Hot-reload capability maintained
- Environment variable support
- Optimized Docker container with Alpine Linux

Breaking Changes:
- Moved main entry from index.js to src/index.js
- Updated configuration structure for v14 compatibility
- Replaced deprecated voice APIs with @discordjs/voice
- Updated audio dependencies (opus, ffmpeg)

🤖 Generated with [Claude Code](https://claude.ai/code)

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

.nvmrc

@@ -0,0 +1 @@
+22