feat: change download flows to download as .zip file (#2870)

* 📝 (flows.py): Add endpoint to download multiple flows as a zip file
📝 (constants.ts): Add FLOWS constant for API endpoint
📝 (index.ts): Add use-post-download-multiple-flows query function
📝 (use-post-download-multiple-flows.ts): Implement function to download multiple flows as a zip file
📝 (index.tsx): Import usePostDownloadMultipleFlows in componentsComponent
📝 (index.tsx): Implement handleExport function to download multiple flows as a zip file
📝 (index.tsx): Update handleExport function to handle downloading and saving the zip file
📝 (headerComponent.tsx): Add shouldSelectAll state and setShouldSelectAll function to manage select all functionality

* formatting file

* 📝 (flows.py): Remove download_file endpoint and refactor download_multiple_file to support downloading multiple flows as a zip file
📝 (index.tsx): Refactor export functionality to handle exporting multiple flows as a zip file or a single flow as a JSON file
🔧 (use-post-download-multiple-flows.ts): Update API endpoint for downloading flows
🔧 (index.tsx): Remove unused imports and functions related to exporting flows
🔧 (reactflowUtils.ts): Remove unused downloadFlows function and related imports

* [autofix.ci] apply automated fixes

* 📝 (flows.py): remove unnecessary whitespace and improve code readability by aligning function parameters in download_multiple_file function

---------

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>

src/backend/tests/unit/test_database.py

@@ -1,3 +1,4 @@
+import json
 from uuid import UUID, uuid4
 
 import orjson
@@ -197,26 +198,27 @@ def test_download_file(
     )
     db_manager = get_db_service()
     with session_getter(db_manager) as session:
+        saved_flows = []
         for flow in flow_list.flows:
             flow.user_id = active_user.id
             db_flow = Flow.model_validate(flow, from_attributes=True)
             session.add(db_flow)
+            saved_flows.append(db_flow)
         session.commit()
-    # Make request to endpoint
-    response = client.get("api/v1/flows/download/", headers=logged_in_headers)
+        # Make request to endpoint inside the session context
+        flow_ids = [str(db_flow.id) for db_flow in saved_flows]  # Convert UUIDs to strings
+        flow_ids_json = json.dumps(flow_ids)
+        response = client.post(
+            "api/v1/flows/download/",
+            data=flow_ids_json,
+            headers={**logged_in_headers, "Content-Type": "application/json"},
+        )
     # Check response status code
     assert response.status_code == 200, response.json()
     # Check response data
-    response_data = response.json()["flows"]
-    starter_projects = load_starter_projects()
-    number_of_projects = len(starter_projects) + len(flow_list.flows)
-    assert len(response_data) == number_of_projects, response_data
-    assert response_data[0]["name"] == "Flow 1"
-    assert response_data[0]["description"] == "description"
-    assert response_data[0]["data"] == data
-    assert response_data[1]["name"] == "Flow 2"
-    assert response_data[1]["description"] == "description"
-    assert response_data[1]["data"] == data
+    # Since the endpoint now returns a zip file, we need to check the content type and the filename in the headers
+    assert response.headers["Content-Type"] == "application/x-zip-compressed"
+    assert "attachment; filename=" in response.headers["Content-Disposition"]
 
 
 def test_create_flow_with_invalid_data(client: TestClient, active_user, logged_in_headers):