ci: 工具缓存 composite action 修 nextest 安装

.github/actions/setup-tools/action.yml

@@ -0,0 +1,39 @@
+name: Setup tools (sccache / mold / nextest)
+
+# 工具缓存：sccache、mold、nextest 统一装到 ~/oxide-tools/bin，按固定 key 跨 run
+# 持久缓存。首跑各 job 各装一次（冗余但一次性），之后每个 run 直接 restore、
+# 秒级。nextest 走官方预编译二进制直下，不依赖 main 分支安装脚本（脚本会被移动
+# 而 404）。sccache 与 mold 经 apt 装到 /usr/bin 后拷入 ~/oxide-tools/bin，
+# 使缓存路径落在用户可写目录（/usr/bin 缓存受权限限制）。
+description: 恢复工具缓存；缺失时安装 sccache、mold、nextest 并存缓存
+
+runs:
+  using: composite
+  steps:
+    - name: Restore tool cache
+      id: tool-cache
+      uses: actions/cache/restore@v4
+      with:
+        path: ~/oxide-tools/bin
+        key: oxide-tools-ubuntu-v1
+
+    - name: Install tools (cache miss)
+      if: steps.tool-cache.outputs.cache-hit != 'true'
+      shell: bash
+      run: |
+        sudo apt-get update -y
+        sudo apt-get install -y sccache mold
+        mkdir -p "$HOME/oxide-tools/bin"
+        cp /usr/bin/sccache /usr/bin/mold "$HOME/oxide-tools/bin/"
+        curl -LsSf https://get.nexte.st/latest/linux | tar zxf - -C "$HOME/oxide-tools/bin"
+
+    - name: Add tools to PATH
+      shell: bash
+      run: echo "$HOME/oxide-tools/bin" >> "$GITHUB_PATH"
+
+    - name: Save tool cache
+      if: steps.tool-cache.outputs.cache-hit != 'true'
+      uses: actions/cache/save@v4
+      with:
+        path: ~/oxide-tools/bin
+        key: oxide-tools-ubuntu-v1