Fix Linux AppImage build: pin ubuntu-22.04 and disable strip

ubuntu-latest switched to 24.04 which has libraries with .relr.dyn
sections that linuxdeploy's bundled eu-strip cannot handle, causing
consistent "failed to run linuxdeploy" errors.

Pin to ubuntu-22.04 (also better glibc compat for AppImage) and set
NO_STRIP=true as a safety net.

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

.github/workflows/desktop-release.yml

@@ -201,7 +201,7 @@ jobs:
     permissions:
       contents: write
       packages: read
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
 
     steps:
       - uses: actions/checkout@v4
@@ -324,6 +324,7 @@ jobs:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           TAURI_SIGNING_PRIVATE_KEY: ${{ secrets.TAURI_SIGNING_PRIVATE_KEY }}
           TAURI_SIGNING_PRIVATE_KEY_PASSWORD: ${{ secrets.TAURI_SIGNING_PRIVATE_KEY_PASSWORD }}
+          NO_STRIP: "true"
         with:
           projectPath: packages/desktop
           tagName: ${{ env.RELEASE_TAG }}