fix: validate extra schedules and localize validation errors

Reject invalid extra_schedules with HTTP 400 before create or update reaches the task service. Preserve omitted, null and empty extras, supported cron syntax, and additional metadata.

Localize missing rules, invalid string and array types, and non-object extra entries through the existing per-request translation middleware. Cover POST/PUT rejection without mutations, dynamic English/Chinese switching, and stable error paths.

Validation: 9 related regression tests passed on current develop; backend build passed. The API validation fix also passed full regression and isolated develop/debian-dev acceptance.

Refs #3099

test/back/dynamic-locales.test.cjs

@@ -22,7 +22,7 @@ const {
 } = require('../../back/validation/schedule');
 const upgrade = require('../../cli/src/internal/maintenance/upgradeArtifacts.cjs');
 
-function responseFor(schema, value) {
+function responseFor(schema, value, fullResponse = false) {
   const validation = schema.validate(value).error;
   assert.ok(validation);
   const error = new CelebrateError('Validation failed', { celebrated: true });
@@ -41,7 +41,7 @@ function responseFor(schema, value) {
   validationErrors(error, {}, res, (err) => {
     throw err;
   });
-  return response.validation.body.message;
+  return fullResponse ? response : response.validation.body.message;
 }
 
 test('compiled validation schemas follow live language changes without altering field paths', () => {
@@ -75,6 +75,100 @@ test('compiled validation schemas follow live language changes without altering
   setLang('zh');
 });
 
+test('cron structure errors switch languages while retaining status and field paths', (t) => {
+  const schema = Joi.object(commonCronSchema);
+  const empty = ['定时规则不能为空', 'Schedule rule cannot be empty'];
+  const string = ['定时规则必须是字符串', 'Schedule rule must be a string'];
+  const object = ['额外定时规则必须是对象', 'Extra schedule must be an object'];
+  const array = ['额外定时规则必须是数组', 'Extra schedules must be an array'];
+  const invalid = ['无效的定时规则', 'Invalid schedule rule'];
+  const cases = [
+    [{ schedule: undefined }, 'schedule', empty],
+    [{ schedule: '' }, 'schedule', empty],
+    [{ schedule: 12 }, 'schedule', string],
+    [{ schedule: null }, 'schedule', string],
+    [{ extra_schedules: [{}] }, 'extra_schedules.0.schedule', empty],
+    [
+      { extra_schedules: [{ schedule: '' }] },
+      'extra_schedules.0.schedule',
+      empty,
+    ],
+    [
+      { extra_schedules: [{ schedule: 12 }] },
+      'extra_schedules.0.schedule',
+      string,
+    ],
+    [
+      { extra_schedules: [{ schedule: null }] },
+      'extra_schedules.0.schedule',
+      string,
+    ],
+    [
+      { extra_schedules: [{ schedule: 'invalid' }] },
+      'extra_schedules.0.schedule',
+      invalid,
+    ],
+    [
+      { extra_schedules: [{ schedule: '0 * * * *' }, {}] },
+      'extra_schedules.1.schedule',
+      empty,
+    ],
+    ...[null, '0 * * * *', 12, []].map((item) => [
+      { extra_schedules: [item] },
+      'extra_schedules.0',
+      object,
+    ]),
+    ...['0 * * * *', {}, 12].map((value) => [
+      { extra_schedules: value },
+      'extra_schedules',
+      array,
+    ]),
+  ];
+  t.after(() => setLang('zh', false));
+  for (const lang of ['en', 'zh', 'en']) {
+    setLang(lang, false);
+    for (const [value, field, messages] of cases) {
+      const response = responseFor(
+        schema,
+        {
+          command: 'task valid.js',
+          schedule: '0 * * * *',
+          ...value,
+        },
+        true,
+      );
+      assert.equal(response.statusCode, 400);
+      assert.equal(
+        response.validation.body.message,
+        messages[lang === 'zh' ? 0 : 1],
+        `${lang}: ${field}`,
+      );
+      assert.deepEqual(response.validation.body.keys, [field]);
+    }
+    const multiple = responseFor(
+      schema.prefs({ abortEarly: false }),
+      {
+        command: 'task valid.js',
+        schedule: '0 * * * *',
+        extra_schedules: [{}, { schedule: 12 }, null],
+      },
+      true,
+    );
+    assert.equal(multiple.statusCode, 400);
+    assert.equal(
+      multiple.validation.body.message,
+      [empty, string, object]
+        .map((messages) => messages[lang === 'zh' ? 0 : 1])
+        .join('. '),
+    );
+    assert.deepEqual(multiple.validation.body.keys, [
+      'extra_schedules.0.schedule',
+      'extra_schedules.1.schedule',
+      'extra_schedules.2',
+    ]);
+  }
+});
+
 test('history, upload, initialization and proxy messages resolve dynamically and preserve user text', () => {
   const keys = [
     '请先初始化',