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.

backend/tests/test_removebg.py

@@ -0,0 +1,73 @@
+"""Tests for background removal route — /api/remove-bg."""
+import io
+import os
+import tempfile
+from unittest.mock import MagicMock
+
+from tests.conftest import make_png_bytes, make_pdf_bytes
+
+
+# =========================================================================
+# Feature flag enforcement
+# =========================================================================
+class TestRemoveBgFeatureFlag:
+    def test_removebg_disabled_by_default(self, client):
+        """Should return 403 when FEATURE_EDITOR is off."""
+        data = {"file": (io.BytesIO(make_png_bytes()), "photo.png")}
+        response = client.post(
+            "/api/remove-bg",
+            data=data,
+            content_type="multipart/form-data",
+        )
+        assert response.status_code == 403
+        assert "not enabled" in response.get_json()["error"]
+
+
+# =========================================================================
+# Validation
+# =========================================================================
+class TestRemoveBgValidation:
+    def test_removebg_no_file(self, client, app):
+        """Should return 400 when no file provided."""
+        app.config["FEATURE_EDITOR"] = True
+        response = client.post("/api/remove-bg")
+        assert response.status_code == 400
+        assert "No file" in response.get_json()["error"]
+
+
+# =========================================================================
+# Success paths
+# =========================================================================
+class TestRemoveBgSuccess:
+    def test_removebg_success(self, client, app, monkeypatch):
+        """Should return 202 with task_id when valid image provided."""
+        app.config["FEATURE_EDITOR"] = True
+        mock_task = MagicMock()
+        mock_task.id = "rembg-task-1"
+
+        tmp_dir = tempfile.mkdtemp()
+        save_path = os.path.join(tmp_dir, "mock.png")
+
+        monkeypatch.setattr(
+            "app.routes.removebg.validate_actor_file",
+            lambda f, allowed_types, actor: ("photo.png", "png"),
+        )
+        monkeypatch.setattr(
+            "app.routes.removebg.generate_safe_path",
+            lambda ext, folder_type: ("mock-id", save_path),
+        )
+        monkeypatch.setattr(
+            "app.routes.removebg.remove_bg_task.delay",
+            MagicMock(return_value=mock_task),
+        )
+
+        data = {"file": (io.BytesIO(make_png_bytes()), "photo.png")}
+        response = client.post(
+            "/api/remove-bg",
+            data=data,
+            content_type="multipart/form-data",
+        )
+        assert response.status_code == 202
+        body = response.get_json()
+        assert body["task_id"] == "rembg-task-1"
+        assert "Background removal started" in body["message"]