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/app-server/src/bespoke_event_handling.rs

@@ -179,6 +179,7 @@ pub(crate) async fn apply_bespoke_event_handling(
             cwd,
             reason,
             risk,
+            allow_prefix: _allow_prefix,
             parsed_cmd,
         }) => match api_version {
             ApiVersion::V1 => {