feat: remove duplicate PROPERTIES section heading from Inspector

The panel title already says "Properties" — the section heading was
redundant. Removed from both DynamicPropertiesPanel and EmptyInspector.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/components/DynamicPropertiesPanel.tsx

@@ -199,7 +199,6 @@ export function DynamicPropertiesPanel({
 
   return (
     <div>
-      <h4 className="font-mono-overline mb-2 text-muted-foreground">Properties</h4>
       <div className="flex flex-col gap-2">
         {entry.isA && (
           <div className="flex items-center justify-between">

src/components/Inspector.tsx

@@ -233,7 +233,6 @@ function EmptyInspector() {
   return (
     <>
       <div>
-        <h4 className="font-mono-overline mb-2 text-muted-foreground">Properties</h4>
         <p className="m-0 text-[13px] text-muted-foreground">No note selected</p>
       </div>
       <div>