Fix circular import in config.py backward compatibility shim

The config.py shim was importing from .config (itself) instead of
.config.parser, causing a circular import that prevented AutoAPI
from reading the modules during docs build.

Also exported _parse_config_file in config module __init__ for
backward compatibility.

Fixes CI failure in deploy-preview job.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: robtaylor

chipflow_lib/config.py

@@ -6,8 +6,8 @@
 New code should import directly from chipflow_lib.config instead.
 """
 
-# Re-export from config module for backward compatibility
-from .config import (  # noqa: F401
+# Re-export from config.parser module for backward compatibility
+from .config.parser import (  # noqa: F401
     get_dir_models,
     get_dir_software,
     _parse_config_file,

chipflow_lib/config/__init__.py

@@ -24,6 +24,7 @@
 from .parser import (
     get_dir_models,
     get_dir_software,
+    _parse_config_file,
 )
 
 __all__ = [
@@ -41,4 +42,5 @@
     # Public utilities
     'get_dir_models',
     'get_dir_software',
+    '_parse_config_file',
 ]