fix: use deb+AppImage only in CI, release job continues if build fails

- Add build:linux-ci script (deb + AppImage, no snap — snapcraft not
  available on ubuntu-latest runners without extra setup)
- Switch release.yml linux build to npm run build:linux-ci
- release job: if: always() so Windows artifacts still get released
  even if linux build fails
- Download artifact steps: continue-on-error so missing platform
  doesn't block GitHub Release creation

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

.github/workflows/release.yml

@@ -29,7 +29,7 @@ jobs:
         run: npm test
 
       - name: Build Linux packages
-        run: npm run build:linux
+        run: npm run build:linux-ci
 
       - name: Upload Linux artifacts
         uses: actions/upload-artifact@v4
@@ -96,18 +96,21 @@ jobs:
 
   release:
     needs: [build-linux, build-windows]
+    if: always()
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
 
       - name: Download Linux artifacts
         uses: actions/download-artifact@v4
+        continue-on-error: true
         with:
           name: linux-artifacts
           path: dist
 
       - name: Download Windows artifacts
         uses: actions/download-artifact@v4
+        continue-on-error: true
         with:
           name: windows-artifacts
           path: dist