Rename chipflow_lib to chipflow with backward compatibility

Rename the main package from chipflow_lib to chipflow, maintaining
full backward compatibility through a compatibility shim.

Changes:
- Renamed chipflow_lib/ directory to chipflow/
- Updated all internal imports from chipflow_lib to chipflow
- Created chipflow_lib/ backward compatibility package that re-exports
  from chipflow with deprecation warnings
- Updated pyproject.toml package name and references
- Updated all documentation references from chipflow_lib to chipflow
- Updated test imports and mock patches
- Changed simulatable_interface default base from
  "com.chipflow.chipflow_lib" to "com.chipflow.chipflow"

The chipflow_lib backward compatibility shim:
- Shows deprecation warning on import
- Re-exports all symbols from chipflow via __path__ manipulation
- Allows existing code using chipflow_lib to continue working
- Will be maintained temporarily before removal in future version

All tests pass with the new package structure.

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

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

Author: robtaylor

chipflow/__init__.py

@@ -0,0 +1,42 @@
+# SPDX-License-Identifier: BSD-2-Clause
+"""
+Chipflow library
+
+This is the main entry point for the ChipFlow library, providing tools for
+building ASIC designs using the Amaranth HDL framework.
+"""
+
+import importlib.metadata
+from typing import TYPE_CHECKING
+
+# Import core utilities
+from .utils import (
+    ChipFlowError,
+    ensure_chipflow_root,
+    get_cls_by_reference,
+    get_src_loc,
+)
+
+if TYPE_CHECKING:
+    from .config import Config
+
+__version__ = importlib.metadata.version("chipflow")
+
+
+# Maintain backward compatibility with underscore-prefixed names
+_get_cls_by_reference = get_cls_by_reference
+_ensure_chipflow_root = ensure_chipflow_root
+_get_src_loc = get_src_loc
+
+
+def _parse_config() -> 'Config':
+    """Parse the chipflow.toml configuration file."""
+    from .config.parser import _parse_config as config_parse
+    return config_parse()
+
+
+__all__ = [
+    '__version__',
+    'ChipFlowError',
+    'ensure_chipflow_root',
+]

chipflow_lib/_doit.py renamed to chipflow/_doit.py

@@ -3,7 +3,7 @@
 Backward compatibility shim for pin lock functionality.
 
 This module re-exports pin lock functionality from the packaging module.
-New code should import directly from chipflow_lib.packaging instead.
+New code should import directly from chipflow.packaging instead.
 """
 
 # Re-export from packaging module for backward compatibility

chipflow_lib/_pin_lock.py renamed to chipflow/_pin_lock.py

@@ -23,9 +23,9 @@ class UnexpectedError(ChipFlowError):
 
 
 DEFAULT_STEPS = {
-    "silicon": "chipflow_lib.steps.silicon:SiliconStep",
-    "sim": "chipflow_lib.steps.sim:SimStep",
-    "software": "chipflow_lib.steps.software:SoftwareStep"
+    "silicon": "chipflow.steps.silicon:SiliconStep",
+    "sim": "chipflow.steps.sim:SimStep",
+    "software": "chipflow.steps.software:SoftwareStep"
 }