[apps] Improve app installation flow. (#11249)

- [x] Add buttons to start the installation flow and verify installation
completes.
- [x] Hard refresh apps list when the /apps view opens.

codex-rs/tui/src/app_event.rs

@@ -114,6 +114,16 @@ pub(crate) enum AppEvent {
         is_installed: bool,
     },
 
+    /// Open the provided URL in the user's browser.
+    OpenUrlInBrowser {
+        url: String,
+    },
+
+    /// Refresh app connector state and mention bindings.
+    RefreshConnectors {
+        force_refetch: bool,
+    },
+
     InsertHistoryCell(Box<dyn HistoryCell>),
 
     StartCommitAnimation,