fix: add missing system dependencies to PR validation workflow

- Added libgtk-3-dev, libwebkit2gtk-4.1-dev, libappindicator3-dev, librsvg2-dev, patchelf
- These are required for building Tauri applications on Linux
- Matches the dependencies already present in the build workflow

Co-Authored-By: Claude <[email protected]>

Author: Y-RyuZU

.github/workflows/pr-validation.yml

@@ -35,6 +35,11 @@ jobs:
           restore-keys: |
             ${{ runner.os }}-pr-
       
+      - name: Install system dependencies
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y libgtk-3-dev libwebkit2gtk-4.1-dev libappindicator3-dev librsvg2-dev patchelf
+      
       - name: Install dependencies
         run: bun install