fix(jax): setattr case_embd (#5104)

`case_embd` was supported but the JAX backend was not touched.

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## Summary by CodeRabbit

## Release Notes

* **Bug Fixes**
* Improved parameter handling in the fitting module to properly support
the `case_embd` parameter, ensuring it receives consistent treatment and
array conversion as other fitting parameters.

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Author: njzjz

deepmd/jax/fitting/fitting.py

@@ -43,6 +43,7 @@ def setattr_for_general_fitting(name: str, value: Any) -> Any:
         "fparam_inv_std",
         "aparam_avg",
         "aparam_inv_std",
+        "case_embd",
         "default_fparam_tensor",
     }:
         value = to_jax_array(value)

source/tests/array_api_strict/fitting/fitting.py

@@ -31,6 +31,7 @@ def setattr_for_general_fitting(name: str, value: Any) -> Any:
         "fparam_inv_std",
         "aparam_avg",
         "aparam_inv_std",
+        "case_embd",
         "default_fparam_tensor",
     }:
         value = to_array_api_strict_array(value)