feat(templates): add intelligent PR template selection system

- Created specialized PR templates for different change types:
  - Backend template for Go/API changes
  - Frontend template for UI/UX changes
  - Documentation template for docs updates
  - General template for mixed changes
- Simplified default template from 270 to 115 lines
- Added GitHub Action for automatic template suggestion based on file types
- Auto-labels PRs with appropriate categories (backend/frontend/documentation)
- Provides friendly suggestions when default template is used

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: tinkle-community <tinklefund@gmail.com>

.github/PULL_REQUEST_TEMPLATE/backend.md

@@ -0,0 +1,130 @@
+# Pull Request - Backend | 后端 PR
+
+> **💡 提示 Tip:** 推荐 PR 标题格式 `type(scope): description`
+> 例如: `feat(trader): add new strategy` | `fix(api): resolve auth issue`
+
+---
+
+## 📝 Description | 描述
+
+**English:**
+
+
+**中文：**
+
+
+---
+
+## 🎯 Type of Change | 变更类型
+
+- [ ] 🐛 Bug fix | 修复 Bug
+- [ ] ✨ New feature | 新功能
+- [ ] 💥 Breaking change | 破坏性变更
+- [ ] ♻️ Refactoring | 重构
+- [ ] ⚡ Performance improvement | 性能优化
+- [ ] 🔒 Security fix | 安全修复
+- [ ] 🔧 Build/config change | 构建/配置变更
+
+---
+
+## 🔗 Related Issues | 相关 Issue
+
+- Closes # | 关闭 #
+- Related to # | 相关 #
+
+---
+
+## 📋 Changes Made | 具体变更
+
+**English:**
+-
+-
+
+**中文：**
+-
+-
+
+---
+
+## 🧪 Testing | 测试
+
+### Test Environment | 测试环境
+- **OS | 操作系统:**
+- **Go Version | Go 版本:**
+- **Exchange | 交易所:** [if applicable | 如适用]
+
+### Manual Testing | 手动测试
+- [ ] Tested locally | 本地测试通过
+- [ ] Tested on testnet | 测试网测试通过（交易所集成相关）
+- [ ] Unit tests pass | 单元测试通过
+- [ ] Verified no existing functionality broke | 确认没有破坏现有功能
+
+### Test Results | 测试结果
+```
+Test output here | 测试输出
+```
+
+---
+
+## 🔒 Security Considerations | 安全考虑
+
+- [ ] No API keys or secrets hardcoded | 没有硬编码 API 密钥
+- [ ] User inputs properly validated | 用户输入已正确验证
+- [ ] No SQL injection vulnerabilities | 无 SQL 注入漏洞
+- [ ] Authentication/authorization properly handled | 认证/授权正确处理
+- [ ] Sensitive data is encrypted | 敏感数据已加密
+- [ ] N/A (not security-related) | 不适用
+
+---
+
+## ⚡ Performance Impact | 性能影响
+
+- [ ] No significant performance impact | 无显著性能影响
+- [ ] Performance improved | 性能提升
+- [ ] Performance may be impacted (explain below) | 性能可能受影响
+
+**If impacted, explain | 如果受影响，请说明：**
+
+
+---
+
+## ✅ Checklist | 检查清单
+
+### Code Quality | 代码质量
+- [ ] Code follows project style | 代码遵循项目风格
+- [ ] Self-review completed | 已完成代码自查
+- [ ] Comments added for complex logic | 已添加必要注释
+- [ ] Code compiles successfully | 代码编译成功 (`go build`)
+- [ ] Ran `go fmt` | 已运行 `go fmt`
+
+### Documentation | 文档
+- [ ] Updated relevant documentation | 已更新相关文档
+- [ ] Added inline comments where necessary | 已添加必要的代码注释
+- [ ] Updated API documentation (if applicable) | 已更新 API 文档
+
+### Git
+- [ ] Commits follow conventional format | 提交遵循 Conventional Commits 格式
+- [ ] Rebased on latest `dev` branch | 已 rebase 到最新 `dev` 分支
+- [ ] No merge conflicts | 无合并冲突
+
+---
+
+## 📚 Additional Notes | 补充说明
+
+**English:**
+
+
+**中文：**
+
+
+---
+
+**By submitting this PR, I confirm | 提交此 PR，我确认：**
+
+- [ ] I have read the [Contributing Guidelines](../../CONTRIBUTING.md) | 已阅读贡献指南
+- [ ] I agree to the [Code of Conduct](../../CODE_OF_CONDUCT.md) | 同意行为准则
+- [ ] My contribution is licensed under AGPL-3.0 | 贡献遵循 AGPL-3.0 许可证
+
+---
+
+🌟 **Thank you for your contribution! | 感谢你的贡献！**