feat: v0.5.0 - provider icon actions, duplicate & connectivity test, dashboard chart fixes

- ProviderList: icon buttons (edit/copy/test/delete) via lucide-react, speed-test badge before enable/switch button
- Duplicate provider: deep-copy provider + models as xxx-copy
- test_connectivity command (cc-switch semantics: GET base_url, any HTTP response = reachable), latency badge green/orange/red, auto-dismiss 6s
- Dashboard: daily bars anchored to panel bottom, Card flex height fix (heatmap stays content-height)

src-tauri/src/lib.rs

@@ -99,6 +99,7 @@ pub fn run() {
             commands::open_agent_config_dir,
             commands::get_app_version,
             commands::list_provider_models,
+            commands::test_connectivity,
             commands::debug_log,
             commands::get_app_setting,
             commands::set_app_setting,