fix: robust Linux CI — root workspace install, split build steps, skip codesign

- npm install at root with --ignore-scripts --legacy-peer-deps
  (prevents node-windows and other Windows postinstall scripts failing)
- CSC_IDENTITY_AUTO_DISCOVERY=false disables electron-builder cert search
- Split vite build, standalone bundle, and electron-builder into separate steps
  so failures are easier to identify in CI logs
- Added libarchive-tools for AppImage generation

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.github/workflows/build-linux.yml

@@ -24,27 +24,32 @@ jobs:
       - name: Install Linux build tools
         run: |
           sudo apt-get update
-          sudo apt-get install -y rpm fakeroot dpkg
+          sudo apt-get install -y rpm fakeroot dpkg libarchive-tools
 
-      - name: Install dependencies (skip Windows-only postinstall scripts)
-        run: npm install --ignore-scripts
+      - name: Install root workspace dependencies
+        run: npm install --ignore-scripts --legacy-peer-deps
+
+      - name: Vite build
+        run: npx electron-vite build
         working-directory: apps/desktop
 
-      - name: Rebuild native modules for Electron
-        run: npx electron-rebuild --version 33.4.11
+      - name: Bundle standalone scheduler
+        run: node scripts/bundle-standalone.js
         working-directory: apps/desktop
 
-      - name: Build Linux packages (x64)
-        run: npx electron-vite build && node scripts/bundle-standalone.js && npx electron-builder --linux --x64
+      - name: Build Linux x64 packages
+        run: npx electron-builder --linux --x64
         working-directory: apps/desktop
         env:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          CSC_IDENTITY_AUTO_DISCOVERY: "false"
 
-      - name: Build Linux packages (arm64)
+      - name: Build Linux arm64 packages
         run: npx electron-builder --linux --arm64
         working-directory: apps/desktop
         env:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          CSC_IDENTITY_AUTO_DISCOVERY: "false"
 
       - name: List build output
         run: ls -lh apps/desktop/dist/