Extract database operations to db.ts, rendering utilities to render.js, and UI handlers to ui.js. This keeps files under 500 lines and improves maintainability. Also fix all lint issues: - Replace 'as any' with proper message type interfaces - Remove unused isReady variable - Wrap switch case blocks with braces - Replace window with globalThis Implements: 09cd703 Assisted-by: Claude Sonnet 4.5 via Crush