Add RPM target for Linux, install 7z fallback on Windows

- Add rpm to bundle targets and install rpm on Linux CI
- Upload both .deb and .rpm from Linux build
- Install 7-Zip via choco if not already available on Windows runner

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

src-tauri/tauri.conf.json

@@ -31,7 +31,7 @@
   },
   "bundle": {
     "active": true,
-    "targets": ["deb", "msi", "dmg"],
+    "targets": ["deb", "rpm", "msi", "dmg"],
     "icon": [
       "icons/32x32.png",
       "icons/128x128.png",