Reduce index.ts from 724 to 458 lines (37% reduction):
- Extract config loading to plugin-config.ts
- Extract ModelCacheState to plugin-state.ts
- Extract config handler to plugin-handlers/config-handler.ts
All 408 tests pass, TypeScript typecheck clean.
🤖 Generated with assistance of OhMyOpenCode (https://github.com/code-yeongyu/oh-my-opencode)
