fix(spatial-office#12): show agent name labels only on hover

Per design-critique-1 Issue 3 (P1), agent name labels were always
visible and stacked into unreadable text when agents were near
each other. Now matches Stardew Valley convention: name shows
on hover only.

Single conditional change. The hover tooltip (Html overlay with
status + current task) is unchanged.

packages/frontend/src/AgentSprite.jsx

@@ -132,22 +132,24 @@ export default function AgentSprite({ agent, hovered, onHover }) {
         />
       </mesh>
 
-      {/* Agent name label */}
-      <Text
-        position={
-          targetPos
-            ? [targetPos[0], 0.7, targetPos[2]]
-            : [0, 0.7, 0]
-        }
-        fontSize={0.15}
-        color={agent.activity === 'offline' ? '#888888' : '#ffffff'}
-        anchorX="center"
-        anchorY="middle"
-        outlineWidth={0.01}
-        outlineColor="#000000"
-      >
-        {agent.name}
-      </Text>
+      {/* Agent name label — hover only (per design-critique-1 Issue 3, P1) */}
+      {hovered && (
+        <Text
+          position={
+            targetPos
+              ? [targetPos[0], 0.7, targetPos[2]]
+              : [0, 0.7, 0]
+          }
+          fontSize={0.15}
+          color={agent.activity === 'offline' ? '#888888' : '#ffffff'}
+          anchorX="center"
+          anchorY="middle"
+          outlineWidth={0.01}
+          outlineColor="#000000"
+        >
+          {agent.name}
+        </Text>
+      )}
 
       {/* Hover tooltip */}
       {hovered && (