fix(07-07): #06-09-5 warn code 178 for unloaded save keys

- core.ts loadState: 差集方向改为 loaded.difference(total)，178 = 存档出现但未加载的 key
- saveablesRoundTrip.test.ts:322-334 改写为「缺 key 不触发 178、仍触发 177」负向见证并更名
- saveablesRoundTrip.test.ts:337-349 取消 it.skip，承担「多出 key 触发 178」正向见证

packages-user/data-state/src/core.ts

@@ -530,7 +530,7 @@ export class CoreState implements ICoreState {
         }
         const loaded = new Set<string>(state.keys());
         const total = new Set(this.saveables.keys());
-        const remain = total.difference(loaded);
+        const remain = loaded.difference(total);
         if (remain.size > 0) {
             const ids = [...remain].join(' | ');
             logger.warn(178, ids);