feat: 初始化PyFlowX轻量级DAG任务调度库

实现完整的DAG任务调度核心功能，包括：
1.  支持同步/异步/线程三种执行策略
2.  自动上下文注入，无需手动绑定任务依赖
3.  内置状态后端，支持断点续跑
4.  提供完整的测试用例与示例代码
5.  添加CI/CD配置与发布流程

.github/workflows/ci.yml

@@ -0,0 +1,131 @@
+name: CI
+
+on:
+  push:
+    branches: [main, develop]
+  pull_request:
+    branches: [main, develop]
+  workflow_dispatch:
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  # ─────────────────────────────────────────────────────────────
+  # 后端：多平台 × 多 Python 版本矩阵测试
+  # ─────────────────────────────────────────────────────────────
+  backend-test:
+    name: Backend (${{ matrix.os }} / py${{ matrix.python-version }})
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, windows-latest, macos-latest]
+        python-version: ['3.13', '3.14']
+        exclude:
+          # macOS + py3.14 暂时跳过（部分依赖未发布 wheel）
+          - os: macos-latest
+            python-version: '3.14'
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: 安装 uv
+        uses: astral-sh/setup-uv@v5
+        with:
+          version: latest
+          enable-cache: true
+          cache-dependency-glob: uv.lock
+
+      - name: 设置 Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v5
+        with:
+          python-version: ${{ matrix.python-version }}
+
+      - name: 安装依赖
+        run: uv sync --extra dev --frozen
+
+      - name: Ruff 检查
+        run: uv run ruff check backend/endo tests
+
+      - name: Ruff 格式检查
+        run: uv run ruff format --check backend/endo tests
+
+      - name: 运行测试
+        env:
+          PYTHONPATH: backend
+        run: uv run pytest -v --cov=endo --cov-report=xml --cov-report=term-missing
+
+      - name: 上传覆盖率
+        if: matrix.os == 'ubuntu-latest' && matrix.python-version == '3.13'
+        uses: actions/upload-artifact@v4
+        with:
+          name: coverage-${{ matrix.os }}-py${{ matrix.python-version }}
+          path: coverage.xml
+          retention-days: 7
+
+  # ─────────────────────────────────────────────────────────────
+  # 前端：多平台构建验证
+  # ─────────────────────────────────────────────────────────────
+  frontend-build:
+    name: Frontend (${{ matrix.os }} / node${{ matrix.node-version }})
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, windows-latest, macos-latest]
+        node-version: [20, 22]
+    defaults:
+      run:
+        working-directory: frontend
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: 安装 pnpm
+        uses: pnpm/action-setup@v4
+        with:
+          version: 9
+
+      - name: 设置 Node ${{ matrix.node-version }}
+        uses: actions/setup-node@v4
+        with:
+          node-version: ${{ matrix.node-version }}
+          cache: pnpm
+          cache-dependency-path: frontend/pnpm-lock.yaml
+
+      - name: 安装依赖
+        run: pnpm install --frozen-lockfile
+
+      - name: TypeScript 类型检查
+        run: npx tsc --noEmit -p tsconfig.app.json
+
+      - name: 构建
+        run: pnpm run build
+
+      - name: 上传构建产物
+        if: matrix.os == 'ubuntu-latest' && matrix.node-version == 22
+        uses: actions/upload-artifact@v4
+        with:
+          name: frontend-dist
+          path: frontend/dist
+          retention-days: 7
+
+  # ─────────────────────────────────────────────────────────────
+  # 聚合：所有测试通过后才标记完成
+  # ─────────────────────────────────────────────────────────────
+  ci-pass:
+    name: CI Pass
+    runs-on: ubuntu-latest
+    needs: [backend-test, frontend-build]
+    if: always()
+    steps:
+      - name: 检查依赖任务结果
+        if: ${{ needs.backend-test.result != 'success' || needs.frontend-build.result != 'success' }}
+        run: |
+          echo "backend-test: ${{ needs.backend-test.result }}"
+          echo "frontend-build: ${{ needs.frontend-build.result }}"
+          exit 1
+      - name: 全部通过
+        run: echo "✅ 所有 CI 检查通过"