chore: add GitHub PR template

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

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,46 @@
+## Thinking Path
+
+<!--
+  Required. Trace your reasoning from the top of the project down to this
+  specific change. Start with what Paperclip is, then narrow through the
+  subsystem, the problem, and why this PR exists. Use blockquote style.
+  See CONTRIBUTING.md for full examples.
+-->
+
+> - Paperclip orchestrates AI agents for zero-human companies
+> - ...
+> - This pull request ...
+
+## What Changed
+
+<!-- Bullet list of concrete changes. One bullet per logical unit. -->
+
+-
+
+## Verification
+
+<!--
+  How can a reviewer confirm this works? Include test commands, manual
+  steps, or both. For UI changes, include before/after screenshots.
+-->
+
+-
+
+## Risks
+
+<!--
+  What could go wrong? Mention migration safety, breaking changes,
+  behavioral shifts, or "Low risk" if genuinely minor.
+-->
+
+-
+
+## Checklist
+
+- [ ] I have included a thinking path that traces from project context to this change
+- [ ] I have run tests locally and they pass
+- [ ] I have added or updated tests where applicable
+- [ ] If this change affects the UI, I have included before/after screenshots
+- [ ] I have updated relevant documentation to reflect my changes
+- [ ] I have considered and documented any risks above
+- [ ] I will address all Greptile and reviewer comments before requesting merge