feat: add Pick placeholder for random selection from list

src/services/pick.ts

@@ -0,0 +1,19 @@
+import type { generationData } from '@/types/SillyTavern'
+
+const pickPlaceholderRegex = /%%pick::([\w\W]*?)%%/g
+
+export const setupPickPlaceholders = () => {
+  const { eventTypes, eventSource } = SillyTavern.getContext()
+  eventSource.on(eventTypes.GENERATE_AFTER_DATA, (chat: generationData) => {
+    chat.prompt = chat.prompt.replaceAll(
+      pickPlaceholderRegex,
+      (_, optionsString: string) => {
+        const options = optionsString.split('::')
+        if (options.length === 0) {
+          return ''
+        }
+        return options[Math.floor(Math.random() * options.length)] ?? ''
+      }
+    )
+  })
+}