v0.6.19

Added

• Added AST.diff(changed: true) / Pi.AST.diff/1 for syntax-aware review of Elixir git changes before reading textual patches.
• elixir_ast_replace dry-runs now include ExAST semantic edit summaries alongside textual patch details.

Changed

• Elixir agent guidance now prefers semantic diffs for Elixir code review before large or truncated git diff output.
• Elixir syntax diff output now groups evidence by file/module and separates public API edits from private helper changes.