chore: import upstream snapshot with attribution

.github/pull_request_template.md

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+## Summary
+
+- Describe the user-facing or operational change.
+
+## Related Issues
+
+- Closes #
+- Related to #
+
+## Validation
+
+- [ ] `npm run lint`
+- [ ] `npm run test:unit`
+- [ ] `npm run test:coverage`
+- [ ] Coverage is still `>= 60%` for statements, lines, functions, and branches
+- [ ] SonarQube PR analysis is green or any remaining issues are explicitly documented below
+
+## Tests Added Or Updated
+
+- List every changed or added automated test file.
+- If no production code changed, state that here.
+
+## Coverage Notes
+
+- If this PR changes `src/`, `open-sse/`, `electron/`, or `bin/`, explain which tests cover the change.
+- If coverage moved down in any touched file, explain why and what follow-up task will recover it.
+
+## Reviewer Notes
+
+- Call out any risky areas, migrations, feature flags, or manual validation that reviewers should know about.