feat: add biome formatter

[vrcprl]

Adds Biome formatter support as an alternative to Prettier, with full backward compatibility.

Changes

Configuration

• Added formatter field to i18n.json schema (v1.8 → v1.9)

• Accepts "prettier" | "biome" | undefined

• Defaults to Prettier when undefined (backward compatible)

  Implementation

• Created /packages/cli/src/cli/loaders/formatters/ directory structure

• _base.ts: Shared formatter logic (DRY principle)

• prettier.ts: Prettier implementation (unchanged behavior)

• biome.ts: New Biome implementation

• index.ts: Factory for formatter selection

Dependencies

• Added @biomejs/js-api@^0.6.2 to production dependencies
• Added @biomejs/wasm-nodejs@^1.8.3 to production dependencies

Integration

• Updated 9 bucket types to support formatter option (json, yaml, html, markdown, mdx, typescript, flutter, json-dictionary)
• Updated 8 command files to pass formatter config from top-level
• Removed redundant bucket-level formatter indirection

TypeScript

• Fixed unused parameter warning in config.ts (P → _P)

Backward Compatibility

✅ 100% backward compatible

• No formatter field → Uses Prettier if .prettierrc exists, otherwise no formatting
• No config file found → Gracefully skips formatting
• All existing functionality preserved

Testing

Verified:

• Prettier formatting with explicit and implicit config
• Biome formatting with biome.json
• Graceful degradation when config files missing
• Dependencies install correctly in fresh environments