- Add POST /api/templates/pdf for creating templates from PDF files
- Supports base64 content and URL file sources
- Supports external_id upsert, folder assignment, explicit field coords
- Supports embedded {{field;type=x;role=y}} text tag extraction
- Add PUT /api/templates/:id/documents for add/replace/remove operations
- Add Api::DecodeDocumentFile utility for shared base64/URL handling
- Add comprehensive API documentation in docs/API.md
- Add routes for new API endpoints