Convert to database-first configuration with token storage

- Rename config.json → seed.json to clarify seeding purpose
- Update ConfigManager to be database-first with minimal file fallbacks
- Store Discord token in database instead of environment variables
- Remove allowedSfxChannels functionality completely
- Update seeding script to import token from seed.json to database
- Add token field to bot_config table in database schema
- Update Docker volume mount to use seed.json
- Update gitignore to protect seed.json while allowing seed.example.json

Configuration Flow:
1. First run: Import from seed.json to database (one-time seeding)
2. Runtime: All configuration from SQLite database
3. Fallback: Environment variables if database unavailable

Security: All sensitive data now stored in encrypted SQLite database

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

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

docker-compose.yml

@@ -8,8 +8,8 @@ services:
     container_name: discord-bot
     restart: unless-stopped
     volumes:
-      # Configuration files (read-only)
-      - ./config.json:/app/config.json:ro
+      # Seed file for initial database population (read-only)
+      - ./seed.json:/app/seed.json:ro
       - ./conf:/app/conf:ro
       
       # Sound effects directory (read-only)