Fix E402 lint errors in backward compatibility stubs

Add noqa: E402 annotations to imports that intentionally come after
deprecation warnings. The imports need to be after warnings.warn() so
users see the deprecation message when they import these modules.

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

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

Author: robtaylor

chipflow_lib/__init__.py

@@ -22,11 +22,11 @@
 
 # Re-export only the symbols actually used by chipflow-digital-ip and chipflow-examples
 # Top-level exports (used by chipflow-examples)
-from chipflow import ChipFlowError  # noqa: F401
-from chipflow import __version__  # noqa: F401
+from chipflow import ChipFlowError  # noqa: F401, E402
+from chipflow import __version__  # noqa: F401, E402
 
 # Internal API (used by tests and CLI)
-from chipflow import _parse_config, _get_cls_by_reference, _ensure_chipflow_root, _get_src_loc  # noqa: F401
+from chipflow import _parse_config, _get_cls_by_reference, _ensure_chipflow_root, _get_src_loc  # noqa: F401, E402
 
 # Note: Submodule imports (chipflow_lib.platforms, chipflow_lib.steps, chipflow_lib.config)
 # are handled by stub modules in their respective subdirectories

chipflow_lib/config.py

@@ -18,8 +18,8 @@
 )
 
 # Re-export the entire config module (used by chipflow-examples via 'import chipflow_lib.config')
-from chipflow import config as _config
-import sys
+from chipflow import config as _config  # noqa: E402
+import sys  # noqa: E402
 
 # Make this module act as a proxy for chipflow.config
 sys.modules[__name__] = _config

chipflow_lib/platforms/__init__.py

@@ -18,7 +18,7 @@
 )
 
 # Re-export symbols used by chipflow-digital-ip and chipflow-examples
-from chipflow.platforms import (  # noqa: F401
+from chipflow.platforms import (  # noqa: F401, E402
     # Pin signatures (used by both repos)
     BidirIOSignature,
     GPIOSignature,

chipflow_lib/steps/board.py

@@ -18,4 +18,4 @@
 )
 
 # Re-export BoardStep (used by chipflow-examples)
-from chipflow.steps.board import BoardStep  # noqa: F401
+from chipflow.steps.board import BoardStep  # noqa: F401, E402

chipflow_lib/steps/sim.py

@@ -18,4 +18,4 @@
 )
 
 # Re-export SimStep (used by chipflow-examples)
-from chipflow.steps.sim import SimStep  # noqa: F401
+from chipflow.steps.sim import SimStep  # noqa: F401, E402

chipflow_lib/steps/software.py

@@ -18,4 +18,4 @@
 )
 
 # Re-export SoftwareStep (used by chipflow-examples)
-from chipflow.steps.software import SoftwareStep  # noqa: F401
+from chipflow.steps.software import SoftwareStep  # noqa: F401, E402