Fix 29 audit findings across all severity tiers

src/core/integrator.rs

@@ -94,7 +94,7 @@ pub fn integrate(record: &AppImageRecord) -> Result<IntegrationResult, Integrati
         "[Desktop Entry]\n\
          Type=Application\n\
          Name={name}\n\
-         Exec={exec} %U\n\
+         Exec=\"{exec}\" %U\n\
          Icon={icon}\n\
          Categories={categories}\n\
          Comment={comment}\n\
@@ -228,7 +228,7 @@ mod tests {
 
     #[test]
     fn test_integrate_creates_desktop_file() {
-        let dir = tempfile::tempdir().unwrap();
+        let _dir = tempfile::tempdir().unwrap();
         // Override the applications dir for testing by creating the record
         // with a specific path and testing the desktop content generation
         let record = AppImageRecord {