feat(api): implement OpenAPI/REST API for file conversions

- Add comprehensive REST API at /api/v1 with modular structure
- Implement authentication endpoints (register, login, logout, me)
- Add converter listing and format discovery endpoints
- Create job management and file download endpoints
- Add health check endpoint for monitoring
- Set up CORS support for browser-based API clients
- Create API middleware for JWT authentication
- Add environment variables for API configuration
- Include comprehensive API documentation and test script

Infrastructure:
- Enhanced CI/CD workflow for custom Docker registries
- Docker Compose setup with dev, prod, and monitoring profiles
- Claude.ai integration files for development workflow
- Environment-based configuration with .env.development

Known limitations:
- JWT authentication context needs fixing (using ALLOW_UNAUTHENTICATED=true)
- Swagger UI temporarily disabled due to composition error
- File upload endpoint needs multipart/form-data support

The API code is isolated in src/api/ directory to maintain separation
from the existing codebase, making it easy to maintain or contribute back.

package.json

@@ -18,6 +18,8 @@
     "@elysiajs/html": "^1.3.0",
     "@elysiajs/jwt": "^1.3.1",
     "@elysiajs/static": "^1.3.0",
+    "@elysiajs/swagger": "^1.3.1",
+    "@elysiajs/cors": "^1.3.0",
     "@kitajs/html": "^4.2.9",
     "elysia": "^1.3.4",
     "sanitize-filename": "^1.6.3",