feat: Add BEN2 background removal functionality and integrate into SnapForm

- Introduced BEN2 model for background removal in the panel and properties.
- Updated runtime to handle background removal commands and model downloads.
- Implemented background removal logic in worker, including image processing and saving results.
- Enhanced tests to cover new background removal features and ensure proper integration.
- Updated version to 0.9.28 to reflect new features and improvements.

tests/test_bootstrap_runtime.py

@@ -31,6 +31,7 @@ class BootstrapRuntimeTest(unittest.TestCase):
                 runtime_dir=str(runtime_dir),
                 backend="cu128",
                 da3_commit="test-commit",
+                ben2_commit="test-ben2-commit",
                 status=str(root / "status.json"),
             )
             with patch.object(bootstrap, "run") as mocked_run:
@@ -58,6 +59,22 @@ class BootstrapRuntimeTest(unittest.TestCase):
         )
         self.assertEqual(gsplat_call.args[1], {"BUILD_NO_CUDA": "1"})
 
+        ben2_command = next(
+            command
+            for command in commands
+            if any("ben2 @" in str(value) for value in command)
+        )
+        self.assertTrue(
+            any("test-ben2-commit" in str(value) for value in ben2_command)
+        )
+        check_command = commands[-1]
+        self.assertTrue(
+            any(
+                "from ben2 import BEN_Base" in str(value)
+                for value in check_command
+            )
+        )
+
 
 if __name__ == "__main__":
     unittest.main()