fix: convert FileInfo to dicts for response model compatibility

The test creates FileInfo from files.py (with content field) but
enlist_process_queue_response expects FileInfo from processes.py (different
model). Converting via model_dump() resolves Pydantic type validation.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: Rafi-Microsoft

src/backend-api/src/tests/model/test_model_process.py

@@ -104,7 +104,7 @@ def test_response_creation(self):
             user_id="test-user",
             message="Files uploaded successfully",
             process_id="123e4567-e89b-12d3-a456-426614174000",
-            files=files,
+            files=[f.model_dump() for f in files],
         )
 
         assert response.message == "Files uploaded successfully"
@@ -124,7 +124,7 @@ def test_to_base64_basic(self):
 
         response = enlist_process_queue_response(
             user_id="test-user",
-            message="Test message", process_id="test-id", files=files
+            message="Test message", process_id="test-id", files=[f.model_dump() for f in files]
         )
 
         # Test the to_base64 method
@@ -153,7 +153,7 @@ def test_to_base64_content_exclusion(self):
 
         response = enlist_process_queue_response(
             user_id="test-user",
-            message="Files with secret content", process_id="secret-test", files=files
+            message="Files with secret content", process_id="secret-test", files=[f.model_dump() for f in files]
         )
 
         # Get base64 and decode
@@ -194,7 +194,7 @@ def test_to_base64_multiple_files(self):
             user_id="test-user",
             message="Multiple EKS files uploaded",
             process_id="eks-migration-123",
-            files=files,
+            files=[f.model_dump() for f in files],
         )
 
         base64_result = response.to_base64()
@@ -257,7 +257,7 @@ def test_to_base64_special_characters(self):
             user_id="test-user",
             message="Special chars: éñüíçødé",
             process_id="unicode-test-123",
-            files=files,
+            files=[f.model_dump() for f in files],
         )
 
         # Should handle special characters without error
@@ -286,7 +286,7 @@ def test_to_base64_large_response(self):
 
         response = enlist_process_queue_response(
             user_id="test-user",
-            message="Bulk file upload", process_id="bulk-upload-test", files=files
+            message="Bulk file upload", process_id="bulk-upload-test", files=[f.model_dump() for f in files]
         )
 
         base64_result = response.to_base64()
@@ -365,7 +365,7 @@ def test_eks_migration_scenario(self):
             user_id="test-user",
             message="EKS migration files processed successfully",
             process_id="eks-migration-d173cea5-b1a5-4fab-929c-7379165cc96e",
-            files=eks_files,
+            files=[f.model_dump() for f in eks_files],
         )
 
         # Convert to base64 for queue message