feat(data): settings.moderatorsPerDay in load/save JSON

tests/data.test.mjs

@@ -1,5 +1,5 @@
 import assert from 'node:assert/strict';
-import { addHistoryEntries, removeHistoryEntry } from '../js/data.js';
+import { addHistoryEntries, removeHistoryEntry, loadFromJSON, saveToJSON } from '../js/data.js';
 
 function makeState(history = []) {
   return {
@@ -76,4 +76,51 @@ function makeState(history = []) {
   assert.equal(state.history.length, 1, 'no change when employeeId not found');
 }
 
+// loadFromJSON: missing settings → default {moderatorsPerDay: 1}
+{
+  const json = JSON.stringify({
+    employees: [],
+    calendar: { holidays: [], companyClosures: [] },
+    history: []
+  });
+  const loaded = loadFromJSON(json);
+  assert.deepEqual(loaded.settings, { moderatorsPerDay: 1 }, 'default settings when missing');
+}
+
+// loadFromJSON: present settings preserved, moderatorsPerDay clamped to [1,5]
+{
+  const json = JSON.stringify({
+    employees: [], calendar: { holidays: [], companyClosures: [] }, history: [],
+    settings: { moderatorsPerDay: 3 }
+  });
+  const loaded = loadFromJSON(json);
+  assert.equal(loaded.settings.moderatorsPerDay, 3, 'preserved value');
+}
+
+// loadFromJSON: invalid moderatorsPerDay (string, out of range) → fallback to 1
+{
+  const tooHigh = loadFromJSON(JSON.stringify({
+    employees: [], calendar: { holidays: [], companyClosures: [] }, history: [],
+    settings: { moderatorsPerDay: 99 }
+  }));
+  assert.equal(tooHigh.settings.moderatorsPerDay, 1, 'out of range falls back to 1');
+
+  const wrongType = loadFromJSON(JSON.stringify({
+    employees: [], calendar: { holidays: [], companyClosures: [] }, history: [],
+    settings: { moderatorsPerDay: 'two' }
+  }));
+  assert.equal(wrongType.settings.moderatorsPerDay, 1, 'wrong type falls back to 1');
+}
+
+// saveToJSON: settings are serialized
+{
+  const state = {
+    employees: [], calendar: { holidays: [], companyClosures: [] }, history: [],
+    settings: { moderatorsPerDay: 2 }
+  };
+  const json = saveToJSON(state);
+  const parsed = JSON.parse(json);
+  assert.deepEqual(parsed.settings, { moderatorsPerDay: 2 }, 'settings round-trip');
+}
+
 console.log('All data tests passed.');