opencode(run): add queued prompt management (#30103)

Direct run mode previously made submitted follow-up prompts irrevocable while a response was still running. Let users edit or remove queued prompts before dispatch without interrupting the active turn.

packages/opencode/test/cli/run/stream.test.ts

@@ -9,6 +9,7 @@ function footer() {
   const api: FooterApi = {
     isClosed: false,
     onPrompt: () => () => {},
+    onQueuedRemove: () => () => {},
     onClose: () => () => {},
     event: (next) => {
       events.push(next)