feat: add rpm target to electron-builder for Linux distribution (#806)

Added rpm target (x64 + arm64) alongside existing deb and AppImage
targets. No CI changes required since electron-builder handles both
deb and rpm generation under the --linux flag.

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

electron/electron-builder.yml

@@ -95,6 +95,10 @@ linux:
       arch:
         - x64
         - arm64
+    - target: rpm
+      arch:
+        - x64
+        - arm64
 
 # Publish configuration (optional)
 publish: