docs: Add merge commit reminder to stack PR descriptions

Stack PRs must be merged with merge commits, not squash. Add a
reminder to the PR description so reviewers/mergers pick the right
method. This only applies to stack PRs — not standalone PRs or the
collection branch PR.

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

Author: adinauer

.claude/skills/create-java-pr/SKILL.md

@@ -113,6 +113,7 @@ Fill in each section based on the changes being PR'd. Check any checklist items
 - Pass `--base <previous-stack-branch>` so the PR targets the previous branch (first PR in a stack targets the collection branch).
 - Use the stacked PR title format: `<type>(<scope>): [<Topic> <N>] <Subject>` (see `.cursor/rules/pr.mdc` § "PR Title Naming").
 - Include the stack list at the top of the PR body, before the `## :scroll: Description` section (see `.cursor/rules/pr.mdc` § "Stack List in PR Description" for the format).
+- Add a merge method reminder at the very end of the PR body (see `.cursor/rules/pr.mdc` § "Stack List in PR Description" for the exact text). This only applies to stack PRs, not the collection branch PR.
 
 Then continue to Step 5.5 (stacked PRs only) or Step 6.
 

.cursor/rules/pr.mdc

@@ -215,6 +215,14 @@ Format:
 
 No status column — GitHub already shows that. The `---` separates the stack list from the rest of the PR description.
 
+**Merge method reminder:** On stack PRs (not the collection branch PR), add the following line at the very end of the PR description:
+
+```markdown
+> ⚠️ **Merge this PR using a merge commit** (not squash). Only the collection branch is squash-merged into main.
+```
+
+This does not apply to standalone PRs or the collection branch PR.
+
 To update the PR description, use `--body-file` to avoid shell quoting issues with special characters in the body:
 
 ```bash