Apply Self-Review Feedback

Read structured review feedback from a self-review XML file and execute the changes.

XML Reference

Non-obvious semantics (keep in sync with assets/self-review-v1.xsd):

• Line number pairing: A comment has exactly one pair — new-line-start/new-line-end (for added/context lines) OR old-line-start/old-line-end (for deleted lines). Never both. If neither pair is present, it's a file-level comment.
• viewed attribute: true = reviewer looked at this file. false = reviewer did not mark it as viewed. Distinguishes "reviewed, no comments" from "not yet reviewed."
• path on renames: For renamed files (change-type="renamed"), path is the new path.
• change-type values: added, modified, deleted, renamed.

1. Read the Review XML

Read the XML file from $ARGUMENTS or default to ./review.xml. Stop if the file does not exist.