Fix PR

Step 0: Resolve PR & Ensure Correct Branch

0a. Determine Target PR

Check if the user mentioned a PR number or URL in the conversation.

If yes — use that:

PR_NUM=$(gh pr view <number-or-url> --json number --jq .number)
PR_BRANCH=$(gh pr view <number-or-url> --json headRefName --jq .headRefName)

If no — use the current branch's PR:

PR_NUM=$(gh pr view --json number --jq .number)
PR_BRANCH=$(gh pr view --json headRefName --jq .headRefName)