feat: add pull request template for better contribution guidelines

Author: mnriem

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,22 @@
+## Description
+
+<!-- What does this PR do? Why is it needed? -->
+
+## Testing
+
+<!-- How did you test your changes? -->
+
+- [ ] Tested locally with `uv run specify --help`
+- [ ] Ran existing tests with `uv sync && uv run pytest`
+- [ ] Tested with a sample project (if applicable)
+
+## AI Disclosure
+
+<!-- Per our Contributing guidelines, AI assistance must be disclosed. -->
+<!-- See: https://github.com/github/spec-kit/blob/main/CONTRIBUTING.md#ai-contributions-in-spec-kit -->
+
+- [ ] I **did not** use AI assistance for this contribution
+- [ ] I **did** use AI assistance (describe below)
+
+<!-- If you used AI, briefly describe how (e.g., "Code generated by Copilot", "Consulted ChatGPT for approach"): -->
+