feat(dashboard): add click-outside dismissal for autocomplete dropdown

Closes bd-3ny. Added mousedown listener that dismisses the dropdown when
clicking outside both the dropdown and textarea. Uses early return to avoid
registering listeners when dropdown is already closed.

dashboard/components/SimpleInput.js

@@ -74,6 +74,21 @@ export function SimpleInput({ sessionId, status, onRespond, autocompleteConfig =
     }
   }, [filteredSkills.length, selectedIndex]);
 
+  // Click outside dismisses dropdown
+  useEffect(() => {
+    if (!showAutocomplete) return;
+
+    const handleClickOutside = (e) => {
+      if (autocompleteRef.current && !autocompleteRef.current.contains(e.target) &&
+          textareaRef.current && !textareaRef.current.contains(e.target)) {
+        setShowAutocomplete(false);
+      }
+    };
+
+    document.addEventListener('mousedown', handleClickOutside);
+    return () => document.removeEventListener('mousedown', handleClickOutside);
+  }, [showAutocomplete]);
+
   // Insert a selected skill into the text
   const insertSkill = useCallback((skill) => {
     if (!triggerInfo || !autocompleteConfig) return;