feat(tf): implement change-bias command (#4927)

Implements TensorFlow support for the `dp change-bias` command with
proper checkpoint handling and variable restoration. This brings the
TensorFlow backend to feature parity with the PyTorch implementation.

## Key Features

- **Checkpoint file support**: Handles individual checkpoint files
(`.ckpt`, `.meta`, `.data`, `.index`) and frozen models (`.pb`)
- **Proper variable restoration**: Variables are correctly restored from
checkpoints using session initialization before bias modification
- **User-defined bias support**: Supports `-b/--bias-value` option with
proper validation against model type_map
- **Data-based bias calculation**: Leverages existing
`change_energy_bias_lower` functionality for automatic bias computation
- **Checkpoint preservation**: Saves modified variables to separate
checkpoint directory for continued training
- **Cross-backend consistency**: Identical CLI interface and
functionality as PyTorch backend

## Before vs After

**Variable restoration**: 
- Before: `Change energy bias of ['O', 'H'] from [0. 0.] to [calculated
values]` (variables never restored)
- After: `Change energy bias of ['O', 'H'] from [-93.57 -187.15] to
[-93.60 -187.19]` (proper restoration)

**Output**: Creates both updated checkpoint files AND frozen model for
continued training

**Documentation**: Comprehensive documentation covering both TensorFlow
and PyTorch backends with examples and backend-specific details

The implementation includes comprehensive test coverage with real model
training to validate functionality without mocks.

Fixes #4018.

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---------

Signed-off-by: Jinzhe Zeng <[email protected]>
Signed-off-by: Jinzhe Zeng <[email protected]>
Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: njzjz <[email protected]>
Co-authored-by: Jinzhe Zeng <[email protected]>
Co-authored-by: Copilot Autofix powered by AI <62310815+github-advanced-security[bot]@users.noreply.github.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: 4 people

.gitignore

@@ -51,7 +51,12 @@ buildcxx/
 node_modules/
 *.bib.original
 
+# Coverage files
+.coverage
+.coverage.*
+
 # Test output files (temporary)
 test_dp_test/
 test_dp_test_*.out
 *_detail.out
+out.json

deepmd/main.py

@@ -752,12 +752,13 @@ def main_parser() -> argparse.ArgumentParser:
     parser_change_bias = subparsers.add_parser(
         "change-bias",
         parents=[parser_log],
-        help="(Supported backend: PyTorch) Change model out bias according to the input data.",
+        help="Change model out bias according to the input data.",
         formatter_class=RawTextArgumentDefaultsHelpFormatter,
         epilog=textwrap.dedent(
             """\
         examples:
-            dp change-bias model.pt -s data -n 10 -m change
+            dp --pt change-bias model.pt -s data -n 10 -m change
+            dp --tf change-bias model.ckpt -s data -n 10 -m change
         """
         ),
     )

deepmd/tf/entrypoints/__init__.py

@@ -4,6 +4,9 @@
 from ..infer.model_devi import (
     make_model_devi,
 )
+from .change_bias import (
+    change_bias,
+)
 from .compress import (
     compress,
 )
@@ -34,6 +37,7 @@
 )
 
 __all__ = [
+    "change_bias",
     "compress",
     "convert",
     "doc_train_input",