Improve /pull-request skill with structured PR body template

.claude/skills/pull-request/SKILL.md

@@ -35,10 +35,7 @@ are no new commits to open a PR for.
 - If there is only one commit, use its subject line directly
 - If there are multiple commits, synthesize a single summary
 
-**Body:**
-- Explain what changed and why in plain prose
-- Do not just restate the commit messages — add context
-- Keep it concise; one short paragraph is usually enough
+**Body:** Follow the template and rules in [template.md](template.md).
 
 ### Step 3: Show the title and body to the user and ask for confirmation
 

.claude/skills/pull-request/template.md

@@ -0,0 +1,26 @@
+# Pull Request Body Template
+
+```
+## Problem
+<one sentence explaining why this change is needed>
+
+## Changes
+- <what changed and why — add context, do not restate commit messages>
+- <additional change if needed>
+
+## Decisions
+- <ADR title and link, e.g. [ADR-013: Branch protection](docs/decisions/013-branch-protection.md)>
+← omit this section if no new or relevant ADRs
+
+---
+Closes #<issue number>  ← omit if no related issue
+⚠️ Breaking change: <description>  ← omit if no breaking change
+```
+
+## Rules
+
+- Omit the `Decisions` section if no ADRs are new or relevant to this PR
+- Omit the `Closes` line if no related issue; do not guess an issue number
+- Include the breaking change line only if a public API is removed, renamed, or
+  its behavior changes in a way that requires callers to update their code
+- Do not add sections for testing — CI is the test record