fix: persist team changes only after versioned server confirmation

tests/team-data.test.mjs

@@ -0,0 +1,8 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import {validateTeam} from '../src/services/teamData.js';
+test('team data accepts empty roster and rejects malformed or duplicate members',()=>{
+ const valid={id:'qa',name:'QA Uzman',role:'Uzman',email:'qa@example.test'};
+ assert.deepEqual(validateTeam([]),[]);assert.deepEqual(validateTeam([valid]),[valid]);
+ for(const bad of [{},null,[{}],[{...valid,name:' '}],[{...valid,email:'invalid'}],[{...valid,role:null}],[valid,valid]])assert.throws(()=>validateTeam(bad));
+});