fix: blur prompt-input after submit to collapse mobile keyboard (#337)

Steps to reproduce:
1. open app at / on mobile
2. type 1 + 1 into prompt input
3. press "enter" (right-bottom button on the keyboard)

Current behaivour: keyboard shown preserving 50% of the screen

Desired behaivour: keyboard collapsed to utilize available screen

---------

Co-authored-by: choi sung keun <86150470+cgoinglove@users.noreply.github.com>

Author: theuargb

src/components/mention-input.tsx

@@ -1,4 +1,5 @@
 "use client";
+import { useIsMobile } from "@/hooks/use-mobile";
 import Mention from "@tiptap/extension-mention";
 import {
   EditorContent,
@@ -70,6 +71,7 @@ export default function MentionInput({
   onBlur,
   fullWidthSuggestion = false,
 }: MentionInputProps) {
+  const isMobile = useIsMobile();
   const [open, setOpen] = useState(false);
   const position = useRef<{
     top: number;
@@ -209,7 +211,13 @@ export default function MentionInput({
         !e.shiftKey &&
         !e.metaKey &&
         !e.nativeEvent.isComposing;
-      if (isSubmit) onEnter?.();
+      if (isSubmit) {
+        e.preventDefault();
+        onEnter?.();
+        if (isMobile) {
+          editor?.commands.blur();
+        }
+      }
     },
     [editor, onEnter, open],
   );