- Add gear button in header to open account settings modal
- Modal covers Organization, Bank, Account, Logo upload, and Printer Offset fields
- PUT /api/account/:id backend endpoint with full field validation
- Logo file reader with inline preview; only updates logo if a new file is chosen
- CSS for btn-header-icon, settings-section-label, logo-preview, form-row-4
- Add GnuMICR.otf (tracked alongside existing GnuMICR.ttf)
