feat(journal): implement JournalInput with command autocomplete

src/components/journal/index.ts

@@ -41,4 +41,6 @@ export { ConnectionBar } from "./ConnectionBar";
 export { StreamView } from "./StreamView";
 export { StreamMessageCard } from "./StreamMessage";
 export { ComposePanel } from "./ComposePanel";
+export { JournalInput } from "./JournalInput";
 export { DynamicForm } from "./DynamicForm";
+export { useJournalCompletions, invalidateCompletions } from "./completions";