Fix cursor placement in chat composer placeholder

- Changed from flexbox to line-height for vertical centering
- Removed flex from .ProseMirror to fix cursor positioning
- Set line-height: 1.25rem to match min-height for proper alignment
- Removed flex items-center from EditorContent className

This ensures the cursor appears at the correct position when focusing
the input field, rather than after the placeholder text.

src/components/editor/MentionEditor.tsx

@@ -888,10 +888,7 @@ export const MentionEditor = forwardRef<
       <div
         className={`rounded border bg-background transition-colors focus-within:border-primary h-7 flex items-center overflow-hidden px-2 ${className}`}
       >
-        <EditorContent
-          editor={editor}
-          className="flex-1 min-w-0 flex items-center"
-        />
+        <EditorContent editor={editor} className="flex-1 min-w-0" />
       </div>
     );
   },

src/index.css

@@ -282,8 +282,7 @@ body.animating-layout
 /* TipTap Editor Styles */
 .ProseMirror {
   min-height: 1.25rem;
-  display: flex;
-  align-items: center;
+  line-height: 1.25rem;
 }
 
 .ProseMirror:focus {
@@ -292,8 +291,7 @@ body.animating-layout
 
 .ProseMirror p {
   margin: 0;
-  flex: 1;
-  min-width: 0;
+  line-height: 1.25rem;
 }
 
 .ProseMirror p.is-editor-empty:first-child::before {