Add OCR, Background Removal, and PDF Editor features with tests

- Implemented OCR functionality using pytesseract for image and PDF text extraction.
- Added Background Removal service using rembg for image processing.
- Developed PDF Editor service for applying text annotations to PDF files.
- Created corresponding API routes for OCR, Background Removal, and PDF Editor.
- Added frontend components for OCR and Background Removal tools.
- Integrated feature flagging for new tools, ensuring they are disabled by default.
- Implemented comprehensive unit tests for OCR service, PDF editor, and background removal.
- Updated documentation to reflect new features and usage instructions.
- Added translations for new features in English, Arabic, and French.

frontend/src/services/api.ts

@@ -76,6 +76,9 @@ export interface TaskResult {
   pages?: Array<{ page: number; text: string }>;
   procedures_count?: number;
   total_pages?: number;
+  // OCR-specific fields
+  text?: string;
+  char_count?: number;
 }
 
 export interface AuthUser {