UI changes to update and support auto updating (#6075)

Co-authored-by: Claude Opus 4.6 (1M context) <[email protected]>

frontend/scripts/dev-update-test/README.md

@@ -0,0 +1,35 @@
+# Auto-Update Testing
+
+## One command (automated)
+
+```bash
+# First time only:
+npm run tauri:setup-dev-update
+
+# Run tests (builds JRE + JAR + signed bundle, starts server + app, runs checks):
+npm run tauri:test-update-e2e
+
+# Full install test (downloads + installs the update):
+npm run tauri:test-update-e2e:install
+
+# Skip rebuild if bundle already exists:
+bash scripts/dev-update-test/test-update-e2e.sh --skip-build
+```
+
+## Manual testing
+
+```bash
+# Terminal 1 - serve the signed v99.0.0 update:
+npm run tauri:serve-dev-update
+
+# Terminal 2 - run the app at v0.0.1:
+npm run tauri:dev-with-update
+```
+
+Go to Settings > General > Software Updates. Click "Check for Updates" then "Install Now".
+
+## Requires
+
+- Java 21+ JDK (with `jlink`)
+- Node.js, Python 3 (with `pip install websockets`)
+- First-time setup generates signing keys + config override