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/mcp-server/src/codex_tool_runner.rs

@@ -180,6 +180,7 @@ async fn run_codex_tool_session_inner(
                         call_id,
                         reason: _,
                         risk,
+                        allow_prefix: _,
                         parsed_cmd,
                     }) => {
                         handle_exec_approval_request(