fix(skills): harden slash skill activation across chat channels (#3466)

* support slash skill activation

* format slash skill activation

* Preserve slash skill activation with uploads

* Address slash skill review feedback

* Address slash skill follow-up review

* Fix lazy slash skill storage resolution

* Keep slash skill activation out of system prompt

* Address slash skill review issues

* fix: harden slash skill command handling

* feat(frontend): add slash skill autocomplete

* fix: address slash skill review feedback

* fix: preserve slash skill text for IM uploads

frontend/src/components/ai-elements/prompt-input.tsx

@@ -881,6 +881,7 @@ export type PromptInputTextareaProps = ComponentProps<
 
 export const PromptInputTextarea = ({
   onChange,
+  onKeyDown,
   className,
   placeholder = "What would you like to know?",
   ...props
@@ -891,6 +892,10 @@ export const PromptInputTextarea = ({
   const [isComposing, setIsComposing] = useState(false);
 
   const handleKeyDown: KeyboardEventHandler<HTMLTextAreaElement> = (e) => {
+    onKeyDown?.(e);
+    if (e.defaultPrevented) {
+      return;
+    }
     if (e.key === "Enter") {
       if (isIMEComposing(e, isComposing)) {
         return;