Refactor group command handling to enforce server control of turtle movement and reject legacy commands

server/server.js

@@ -1303,18 +1303,15 @@ app.post('/api/groups/:groupId/command', (req, res) => {
     for (const member of members) {
       const turtle = turtles.get(member.turtle_id);
       if (turtle) {
+        // All group commands are state changes — server controls all movement
         if (command === 'set_state' || command === 'setState') {
           const stateName = param?.state || param;
           const stateData = param?.data || {};
           turtle.setState(stateName, stateData);
+          successCount++;
         } else {
-          turtle.pendingLegacyCommands.push({
-            command,
-            param,
-            timestamp: Date.now()
-          });
+          console.log(`⚠️ Legacy group command rejected: ${command}`);
         }
-        successCount++;
       }
     }