feat: auto-persist state to localStorage on every change

js/history.js

@@ -1,4 +1,4 @@
-import { state } from './app.js';
+import { state, saveState } from './app.js';
 import { loadFromJSON, saveToJSON, removeHistoryEntry } from './data.js';
 import { downloadBlob } from './excel.js';
 
@@ -79,6 +79,7 @@ export function renderDataTab() {
       state.employees = loaded.employees;
       state.calendar = loaded.calendar;
       state.history = loaded.history;
+      saveState();
       alert('Daten erfolgreich geladen.');
       renderDataTab();
     } catch (err) {
@@ -136,6 +137,7 @@ function renderHistoryTable() {
     delBtn.style.cssText = 'font-size:11px;padding:2px 6px';
     delBtn.addEventListener('click', () => {
       removeHistoryEntry(state, h.date);
+      saveState();
       renderHistoryTable();
     });
     actionTd.appendChild(delBtn);