Catch Linux cfg drift before release

CI only checked macOS and Windows before merge, so Linux-only Rust paths could fail cargo check for the first time during release packaging. The matrix now includes an Ubuntu lane that runs the same frontend build and backend cargo check, with only the Linux libraries needed for checking Tauri dependencies and no bundle step.

Constraint: Issue #300 asks for PR-time Linux validation while skipping Tauri bundle work.\nRejected: Add Linux release bundle to CI | too slow and duplicates release-tauri.yml.\nConfidence: high\nScope-risk: narrow\nTested: python ci.yml textual assertions; git diff --check; cd openless-all/app && npm run build; cd openless-all/app && cargo check --manifest-path src-tauri/Cargo.toml\nNot-tested: Full GitHub Actions ubuntu-latest runner execution before PR.\nRelated: https://github.com/appergb/openless/issues/300

.github/workflows/ci.yml

@@ -3,8 +3,8 @@ name: CI
 # 多平台跨语言质量门禁。release-tauri.yml 是发版流水线（仅打包构建），这里负责
 # 在合并前快速验证两件事：
 #   1. 前端 typecheck + vite bundle 通过（tsc + vite build，捕获跨 locale 类型 drift）
-#   2. Rust 后端在 macOS / Windows 都能 cargo check 过（捕获 cfg 漏分支 / 平台 API 误用）
-# 跑 build-mac.sh / windows-package-msvc.ps1 太重；只跑轻量 cargo check + vite build。
+#   2. Rust 后端在 macOS / Windows / Linux 都能 cargo check 过（捕获 cfg 漏分支 / 平台 API 误用）
+# 跑 build-mac.sh / windows-package-msvc.ps1 / Tauri bundle 太重；只跑轻量 cargo check + vite build。
 
 on:
   push:
@@ -26,6 +26,9 @@ jobs:
           - os: windows-latest
             label: Windows
             preflight: true
+          - os: ubuntu-latest
+            label: Linux
+            preflight: false
     runs-on: ${{ matrix.os }}
     defaults:
       run:
@@ -45,6 +48,22 @@ jobs:
 
       - uses: dtolnay/rust-toolchain@stable
 
+      - name: Install Linux check dependencies
+        if: runner.os == 'Linux'
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y \
+            build-essential \
+            curl \
+            file \
+            libasound2-dev \
+            libayatana-appindicator3-dev \
+            librsvg2-dev \
+            libssl-dev \
+            libwebkit2gtk-4.1-dev \
+            libxdo-dev \
+            wget
+
       - name: Install frontend dependencies
         run: npm ci