Support separate pattern files for renames vs content replacements

[jlevy]

Summary

Currently, the same patterns are applied to both file content replacements and file path renames (when using --full). There is no way to specify different patterns for each operation.

Details

There is a TODO at line 1638 of repren.py:

# Separate patterns file for renames and replacements

Use cases where separate patterns would be useful:

• Renaming files according to one convention while replacing content with a different pattern
• Using regex features in content patterns that don't make sense for file paths
• Applying broader patterns to content but more conservative patterns to filenames (to avoid accidental directory restructuring)

Suggestion

Add an optional --rename-patterns flag (or --content-patterns) that allows specifying a separate patterns file for renames vs content replacements. When not specified, the existing behavior (same patterns for both) would be preserved.