init: add source code from src.zip

src/commands/btw/index.ts

@@ -0,0 +1,13 @@
+import type { Command } from '../../commands.js'
+
+const btw = {
+  type: 'local-jsx',
+  name: 'btw',
+  description:
+    'Ask a quick side question without interrupting the main conversation',
+  immediate: true,
+  argumentHint: '<question>',
+  load: () => import('./btw.js'),
+} satisfies Command
+
+export default btw