ci: 引入自动化构建流水线（inbox 收件箱 + Actions + 新 README）

.github/workflows/build.yml

@@ -0,0 +1,55 @@
+name: Build
+
+on:
+  push:
+    branches: [main]
+    paths:
+      - "inbox/**"
+      - "scripts/**"
+      - ".github/workflows/build.yml"
+  workflow_dispatch:
+
+permissions:
+  contents: write
+
+concurrency:
+  group: build
+  cancel-in-progress: false
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: 检出仓库
+        uses: actions/checkout@v4
+
+      - name: 安装 Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+
+      - name: 安装依赖
+        run: |
+          pip install Pillow
+          if ! command -v rsvg-convert >/dev/null 2>&1; then
+            sudo apt-get update -qq
+            sudo apt-get install -y -qq librsvg2-bin
+          fi
+
+      - name: 构建
+        id: build
+        env:
+          TINYPNG_KEY: ${{ secrets.TINYPNG_KEY }}
+        run: python scripts/build.py --repo .
+
+      - name: 提交并推送
+        run: |
+          git config user.name "github-actions[bot]"
+          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
+          git add -A
+          if git diff --cached --quiet; then
+            echo "没有需要提交的变更"
+          else
+            git commit -m "ci: 自动构建（新增 ${{ steps.build.outputs.added }} 个图标）"
+            git push
+          fi