test(photos): pick calibration before Mask (#60)

Failing session/UI tests for M2-3: Continue → pickCalibration (not
first-photo Mask proxy), user pick enters Mask on that Source, draft
remembers calibrationIndex, Resume restores. No production change yet (TDD).

frontend/src/capture/session.batch.test.ts

@@ -68,15 +68,16 @@ test('continueBatch is a no-op when batch is empty', () => {
   s.dispose();
 });
 
-test('continueBatch with ≥1 photo advances (M1 bridge: mask on first photo)', async () => {
+test('continueBatch with ≥1 photo advances to pickCalibration (not Mask)', async () => {
+  // #60: Continue must not silently Mask the first photo — user picks calibration next.
   const s = createCaptureSession({ draft: store });
   await s.addToBatch(tinyJpeg('a'));
   await s.addToBatch(tinyJpeg('b'));
   s.continueBatch();
   const cap = get(s.capture);
-  assert.equal(cap.k, 'mask');
-  if (cap.k === 'mask') {
-    assert.ok(cap.source.blob instanceof Blob);
+  assert.equal(cap.k, 'pickCalibration');
+  if (cap.k === 'pickCalibration') {
+    assert.equal(cap.photos.length, 2);
   }
   s.dispose();
 });