feat: remove unused support_array_api decorator (#5200)

The `support_array_api` decorator defined in
`deepmd/dpmodel/array_api.py` was unused metadata that added no
functional value. It set an `array_api_version` attribute on decorated
functions, but this attribute was never checked anywhere in the
codebase.

## Changes

- **Removed decorator definition** from `deepmd/dpmodel/array_api.py`
(30 lines)
- **Removed decorator usages** from:
- `deepmd/dpmodel/utils/env_mat.py` - `compute_smooth_weight()`,
`compute_exp_sw()`
- `deepmd/dpmodel/utils/network.py` - `NativeLayer.call()`,
`get_activation_fn()`
  - `deepmd/dpmodel/utils/type_embed.py` - `TypeEmbedNet.call()`
- **Removed unused test utility** `set_array_api_version()` from
`source/tests/common/dpmodel/array_api/utils.py`
- **Cleaned up imports** - removed `Callable` and
`set_array_api_strict_flags` where no longer needed

Functions previously decorated now have unchanged behavior:

```python
# Before
@support_array_api(version="2023.12")
def compute_smooth_weight(distance: Array, rmin: float, rmax: float) -> Array:
    ...

# After
def compute_smooth_weight(distance: Array, rmin: float, rmax: float) -> Array:
    ...
```

Total: 45 lines deleted across 5 files.

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<details>

<summary>Original prompt</summary>

> 
> ----
> 
> *This section details on the original issue you should resolve*
> 
> <issue_title>[Feature Request] Remove unused support_array_api
decorator to simplify codebase</issue_title>
> <issue_description>### Summary
> 
> Propose to remove the rarely used `support_array_api` decorator
defined at
[deepmd/dpmodel/array_api.py#L21](https://github.com/deepmodeling/deepmd-kit/blob/ef0be638972739463813609729075bf38973dd9d/deepmd/dpmodel/array_api.py#L21)
to simplify and streamline the codebase.
> 
> ### Detailed Description
> 
> The `support_array_api` decorator is present in the codebase but is
used in only a few isolated functions and has not contributed to
significant or widely used features. Its presence now causes unnecessary
clutter and maintenance complexity.
> 
> By removing this unused decorator and its usages, we can improve
overall code maintainability and reduce confusion for contributors. If a
future need for such a decorator arises, it can be revised and
reintroduced when there is a broader adoption scenario.
> 
> ### Further Information, Files, and Links
> 
> _No response_</issue_description>
> 
> ## Comments on the Issue (you are @copilot in this section)
> 
> <comments>
> </comments>
> 


</details>



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- Fixes #5199

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Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: njzjz <9496702+njzjz@users.noreply.github.com>

Author: Copilot

deepmd/dpmodel/array_api.py

@@ -1,9 +1,6 @@
 # SPDX-License-Identifier: LGPL-3.0-or-later
 """Utilities for the array API."""
 
-from collections.abc import (
-    Callable,
-)
 from typing import (
     Any,
 )
@@ -18,33 +15,6 @@
 Array = np.ndarray | Any  # Any to support JAX, PyTorch, etc. arrays
 
 
-def support_array_api(version: str) -> Callable:
-    """Mark a function as supporting the specific version of the array API.
-
-    Parameters
-    ----------
-    version : str
-        The version of the array API
-
-    Returns
-    -------
-    Callable
-        The decorated function
-
-    Examples
-    --------
-    >>> @support_array_api(version="2022.12")
-    ... def f(x):
-    ...     pass
-    """
-
-    def set_version(func: Callable) -> Callable:
-        func.array_api_version = version
-        return func
-
-    return set_version
-
-
 # array api adds take_along_axis in https://github.com/data-apis/array-api/pull/816
 # but it hasn't been released yet
 # below is a pure Python implementation of take_along_axis

deepmd/dpmodel/utils/env_mat.py

@@ -10,15 +10,13 @@
 )
 from deepmd.dpmodel.array_api import (
     Array,
-    support_array_api,
     xp_take_along_axis,
 )
 from deepmd.dpmodel.utils.safe_gradient import (
     safe_for_vector_norm,
 )
 
 
-@support_array_api(version="2023.12")
 def compute_smooth_weight(
     distance: Array,
     rmin: float,
@@ -35,7 +33,6 @@ def compute_smooth_weight(
     return vv
 
 
-@support_array_api(version="2023.12")
 def compute_exp_sw(
     distance: Array,
     rmin: float,

deepmd/dpmodel/utils/network.py

@@ -23,7 +23,6 @@
 )
 from deepmd.dpmodel.array_api import (
     Array,
-    support_array_api,
     xp_add_at,
     xp_bincount,
 )
@@ -259,7 +258,6 @@ def dim_in(self) -> int:
     def dim_out(self) -> int:
         return self.w.shape[1]
 
-    @support_array_api(version="2022.12")
     def call(self, x):  # noqa: ANN001, ANN201
         """Forward pass.
 
@@ -296,7 +294,6 @@ def call(self, x):  # noqa: ANN001, ANN201
         return y
 
 
-@support_array_api(version="2022.12")
 def get_activation_fn(activation_function: str) -> Callable[[np.ndarray], np.ndarray]:
     activation_function = activation_function.lower()
     if activation_function == "tanh":

deepmd/dpmodel/utils/type_embed.py

@@ -8,7 +8,6 @@
 
 from deepmd.dpmodel.array_api import (
     Array,
-    support_array_api,
 )
 from deepmd.dpmodel.common import (
     PRECISION_DICT,
@@ -96,7 +95,6 @@ def __init__(
             trainable=trainable,
         )
 
-    @support_array_api(version="2022.12")
     def call(self) -> Array:
         """Compute the type embedding network."""
         sample_array = self.embedding_net[0]["w"]

source/tests/common/dpmodel/array_api/utils.py

@@ -1,17 +1,10 @@
 # SPDX-License-Identifier: LGPL-3.0-or-later
 import array_api_compat
-from array_api_strict import (
-    set_array_api_strict_flags,
-)
 
 
 class ArrayAPITest:
     """Utils for array API tests."""
 
-    def set_array_api_version(self, func) -> None:
-        """Set the array API version for a function."""
-        set_array_api_strict_flags(api_version=func.array_api_version)
-
     def assert_namespace_equal(self, a, b) -> None:
         """Assert two array has the same namespace."""
         self.assertEqual(