docs: add contribution guidelines and pull request template

.github/pull_request_template.md

@@ -0,0 +1,37 @@
+## Summary
+
+<!-- What changed, and why is it needed? -->
+
+## Related Issue
+
+<!-- Example: Closes #123 -->
+
+## Validation
+
+- [ ] Applicable checks pass: lint, format check, tests, and build
+- [ ] Relevant E2E and manual tests are complete or not applicable
+
+Evidence, screenshots, or compatibility notes:
+
+<!-- Include screenshots for UI changes and `.drawnix` compatibility notes when relevant. -->
+
+## AI Assistance
+
+Did you use AI tools to generate or substantially modify code, tests, or documentation in this pull request?
+
+- [ ] No
+- [ ] Yes
+
+If yes:
+
+- **Tool/model:** <!-- Example: Codex / GPT-5.6 Sol -->
+- **AI-assisted work:** <!-- Affected files or tasks -->
+- **My review and validation:** <!-- What did you personally review and test? -->
+
+- [ ] I reviewed and understand the AI-assisted changes and can explain and maintain them
+
+## Checklist
+
+- [ ] The title and description are in English, and the change is focused
+- [ ] I reviewed and understand every submitted change
+- [ ] Tests, documentation, and translations were updated when needed

CONTRIBUTING.md

@@ -0,0 +1,67 @@
+# Contributing to Drawnix
+
+Thank you for contributing. Bug fixes, tests, documentation, translations, performance improvements, and focused features are welcome.
+
+## Community Language
+
+Drawnix uses English for issues, pull requests, discussions, reviews, commit messages, and contributor documentation. Localized product content is welcome, but contribution discussions should remain in English.
+
+## Before You Start
+
+- Search existing issues and discussions first.
+- Reproduce bugs on the latest `develop` branch.
+- Keep each issue or pull request focused on one problem.
+- Discuss large features, architecture changes, or `.drawnix` format changes before implementation.
+- Verify AI-assisted findings. Do not publish raw AI audit output or batches of unverified issues.
+
+## Local Development
+
+Use the Node.js version in `.nvmrc`.
+
+```bash
+npm ci
+npm run start
+```
+
+Before opening a pull request, run the checks that apply to your change:
+
+```bash
+npm run lint
+npm run format:check
+npm run test
+npm run build
+```
+
+For interaction changes, install the Playwright browsers and run the E2E tests:
+
+```bash
+npx playwright install
+npx nx e2e web-e2e
+```
+
+## Pull Requests
+
+- Target the `develop` branch.
+- Use an English title, description, and clear commit messages.
+- Explain what changed and why; link the related issue when available.
+- Add or update tests for behavior changes.
+- Include screenshots or a recording for visible UI changes.
+- Update documentation and translations when needed.
+- Preserve compatibility with existing `.drawnix` files when changing import, export, clipboard, or serialization behavior.
+- Avoid unrelated formatting, refactoring, or dependency changes.
+
+## AI-Assisted Contributions
+
+AI tools are welcome, but contributors remain responsible for their work. If AI generated or substantially modified code, tests, or documentation, disclose:
+
+- The tool and model, if known
+- What the AI helped with
+- Your human review and testing
+
+You must understand, explain, and maintain the submitted changes. Raw or unverified AI output is not acceptable. Trivial autocomplete, spelling, and formatting assistance do not require disclosure.
+
+Do not provide secrets, private vulnerability details, personal data, or unauthorized content to external AI services.
+
+## License
+
+By contributing, you agree that your contribution will be licensed under the repository's MIT License.

README.md

@@ -126,6 +126,8 @@ docker pull pubuzhixing/drawnix:latest
 
 欢迎任何形式的贡献：
 
+提交 Issue 或 Pull Request 前，请先阅读 [贡献指南](CONTRIBUTING.md)。
+
 - 提 Bug
 
 - 贡献代码
@@ -142,4 +144,4 @@ docker pull pubuzhixing/drawnix:latest
 
 ## License
 
-[MIT License](https://github.com/plait-board/drawnix/blob/master/LICENSE)  
+[MIT License](https://github.com/plait-board/drawnix/blob/master/LICENSE)

README_en.md

@@ -123,6 +123,8 @@ docker pull pubuzhixing/drawnix:latest
 
 Any form of contribution is welcome:
 
+Before opening an issue or pull request, please read the [Contributing Guide](CONTRIBUTING.md).
+
 - Report bugs
 
 - Contribute code
@@ -139,4 +141,4 @@ Special thanks to the company for its strong support for open source projects, a
 
 ## License
 
-[MIT License](https://github.com/plait-board/drawnix/blob/master/LICENSE)
+[MIT License](https://github.com/plait-board/drawnix/blob/master/LICENSE)