fix(skills): prevent premature thread resolution on self-authored PRs

The review bot incorrectly resolved its own technically-correct suggestion
on PR #1583. It had correctly identified that linked worktrees can be on
different mount points (EXDEV on rename), but in a later incremental
review run it accepted the author's less accurate doc comment claiming
".git/ is always on the same filesystem" and resolved the thread.

Add guidance to Step 6 (thread resolution) requiring:
- Verification that the substance was addressed, not just reworded
- Extra skepticism on self-authored PRs where the bot is both author
  and reviewer, creating a bias toward accepting its own code's claims

Evidence: run 23182191893, PR #1583, session e2cae4a2

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: worktrunk-bot

.claude/skills/review-pr/SKILL.md

@@ -318,6 +318,17 @@ After approving or staying silent, monitor CI using the approach from
 After submitting the review, check if any unresolved bot threads have been
 addressed by the new changes. Resolve threads where the suggestion was applied.
 
+**Only resolve if the substance was addressed.** Read both the suggestion and the
+new code — if the author took a different approach, verify its technical accuracy
+before resolving. "Different wording" is not "addressed" when the new wording is
+less accurate than the suggestion. When in doubt, leave the thread open for a
+human reviewer.
+
+**Self-authored PRs are especially risky.** When the bot is both author and
+reviewer, there is a bias toward accepting the code's own claims. Treat
+self-authored thread resolution with extra skepticism — read the code and verify
+the claim independently rather than trusting the doc comment or commit message.
+
 ```bash
 cat > /tmp/review-threads.graphql << 'GRAPHQL'
 query($owner: String!, $repo: String!, $number: Int!) {