chore: improve contribution guidelines and add PR template

.github/ISSUE_TEMPLATE/feature_request.md

@@ -7,6 +7,9 @@ assignees: ''
 
 ---
 
+> [!IMPORTANT]
+> Wait for a maintainer to approve this issue before opening a PR. We'll signal approval with a comment or label. Feature PRs without an approved issue will be closed.
+
 ## ✨ Feature Request
 
 **Is your feature request related to a problem? Please describe.**

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,24 @@
+## Description
+
+<!-- What does this PR do? Why? -->
+
+## Type of change
+
+- [ ] Bug fix
+- [ ] Feature (requires an approved issue — see below)
+- [ ] Refactor / chore
+- [ ] Documentation
+
+## Checklist
+
+- [ ] I have linked the related issue below
+- [ ] My code follows the existing style and conventions
+- [ ] I have tested my changes locally
+- [ ] I have included screenshots for any UI changes
+
+## Linked issue
+
+Closes #<!-- issue number -->
+
+> **Feature PRs without a linked, approved issue will be closed without review.**
+> Open or comment on a [feature request](https://github.com/kanbn/kan/issues/new?template=feature_request.md) first and wait for maintainer approval before building.