whitelist command prefix integration in core and tui (#7033)

this PR enables TUI to approve commands and add their prefixes to an
allowlist:
<img width="708" height="605" alt="Screenshot 2025-11-21 at 4 18 07 PM"
src="https://github.com/user-attachments/assets/56a19893-4553-4770-a881-becf79eeda32"
/>

note: we only show the option to whitelist the command when 
1) command is not multi-part (e.g `git add -A && git commit -m 'hello
world'`)
2) command is not already matched by an existing rule

codex-rs/tui/src/chatwidget.rs

@@ -1074,6 +1074,7 @@ impl ChatWidget {
             command: ev.command,
             reason: ev.reason,
             risk: ev.risk,
+            allow_prefix: ev.allow_prefix,
         };
         self.bottom_pane.push_approval_request(request);
         self.request_redraw();