fix: handle /review arguments in TUI (#8823)

Handle /review <instructions> in the TUI and TUI2 by routing it as a
custom review command instead of plain text, wiring command dispatch and
adding composer coverage so typing /review text starts a review directly
rather than posting a message. User impact: /review with arguments now
kicks off the review flow, previously it would just forward as a plain
command and not actually start a review.

codex-rs/tui2/src/chatwidget.rs

@@ -1500,6 +1500,9 @@ impl ChatWidget {
                     InputResult::Command(cmd) => {
                         self.dispatch_command(cmd);
                     }
+                    InputResult::CommandWithArgs(cmd, args) => {
+                        self.dispatch_command_with_args(cmd, args);
+                    }
                     InputResult::None => {}
                 }
             }
@@ -1665,6 +1668,33 @@ impl ChatWidget {
         }
     }
 
+    fn dispatch_command_with_args(&mut self, cmd: SlashCommand, args: String) {
+        if !cmd.available_during_task() && self.bottom_pane.is_task_running() {
+            let message = format!(
+                "'/{}' is disabled while a task is in progress.",
+                cmd.command()
+            );
+            self.add_to_history(history_cell::new_error_event(message));
+            self.request_redraw();
+            return;
+        }
+
+        let trimmed = args.trim();
+        match cmd {
+            SlashCommand::Review if !trimmed.is_empty() => {
+                self.submit_op(Op::Review {
+                    review_request: ReviewRequest {
+                        target: ReviewTarget::Custom {
+                            instructions: trimmed.to_string(),
+                        },
+                        user_facing_hint: None,
+                    },
+                });
+            }
+            _ => self.dispatch_command(cmd),
+        }
+    }
+
     pub(crate) fn handle_paste(&mut self, text: String) {
         self.bottom_pane.handle_paste(text);
     }