fix: guide EKAP human verification

tests/source-error.test.mjs

@@ -0,0 +1,24 @@
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import { sourceFailure } from '../server/source-error.mjs';
+
+test('EKAP human verification is a manual non-retryable gate', () => {
+  const result = sourceFailure(new Error('EKAP 428: {"code":"HUMAN_VERIFICATION_REQUIRED"}'));
+  assert.equal(result.status, 428);
+  assert.equal(result.body.code, 'HUMAN_VERIFICATION_REQUIRED');
+  assert.equal(result.body.retryable, false);
+  assert.equal(result.body.manualAction, true);
+  assert.equal(result.body.manualUrl, 'https://ekap.kik.gov.tr/EKAP/');
+  assert.match(result.body.error, /kendi tarayıcınızda açıp doğrulamayı tamamlayın/);
+});
+
+test('ordinary upstream failures stay retryable', () => {
+  const result = sourceFailure(new Error('upstream timeout'));
+  assert.equal(result.status, 502);
+  assert.deepEqual(result.body, {
+    success: false,
+    error: 'upstream timeout',
+    code: 'SOURCE_UNAVAILABLE',
+    retryable: true,
+  });
+});