feat: History tab on Upload page with one-click Re-export ZIP

Add a second tab to the Upload page that surfaces the persisted batch
archive and lets the user re-download any 837P batch as a ZIP without
re-parsing the original file.

- Backend: /api/batches now carries per-row claimIds (837P only).
  835 batches return an empty list, which the UI uses as the signal
  to hide the Re-export button on those rows. Avoids an extra
  round-trip to /api/batches/{id} per row.
- Frontend: BatchSummary.claimIds added to the list-endpoint type.
- Upload page: page body wrapped in Tabs.Root with a History trigger
  that mirrors ?tab= in the URL for deep-link round-trip. The
  History tab renders UploadHistory → HistoryTable → HistoryRow with
  a one-click Re-export ZIP button per 837P row. The button calls
  POST /api/batches/{id}/export-837 with the row's claim ids and
  downloads the ZIP via downloadBlob. Falls back to the in-memory
  parsedBatches store when the backend returns no rows so the tab
  stays useful in sample-data mode.
- Backend tests: claimIds present on 837P rows, empty on 835 rows.
- Frontend tests: 13 tests covering tab switching, URL deep-link,
  loading/error/empty states, the 837P-vs-835 button visibility
  split, the Re-export happy path, and the failure toast.

backend/tests/test_api_gets.py

@@ -65,6 +65,42 @@ def test_batches_returns_summary_after_parse(seeded_store):
     assert body["items"][0]["inputFilename"] == "x.txt"
 
 
+def test_batches_includes_claim_ids_for_837p(seeded_store):
+    """The Upload page's History tab renders a Re-export ZIP button per
+    row that fires ``POST /api/batches/{id}/export-837`` with the row's
+    claim ids. Carry those ids in the list response so the UI doesn't
+    need an extra round-trip per row to fetch them."""
+    batches = seeded_store.get("/api/batches", headers=JSON).json()["items"]
+    assert len(batches) == 1
+    item = batches[0]
+    assert item["kind"] == "837p"
+    # claimIds is a non-empty list of the same claim ids that live
+    # inside the parsed result — see `seeded_store` in conftest.py.
+    assert isinstance(item["claimIds"], list)
+    assert len(item["claimIds"]) == 2
+    full = seeded_store.get(f"/api/batches/{item['id']}").json()
+    assert sorted(item["claimIds"]) == sorted(c["claim_id"] for c in full["claims"])
+
+
+def test_batches_claim_ids_empty_for_835(client: TestClient, tmp_path):
+    """835 has no re-export endpoint — the field is always ``[]`` so the
+    History tab can use it as the signal to hide the Re-export button."""
+    src = Path(__file__).parent / "fixtures" / "minimal_835.txt"
+    files = {"file": ("minimal_835.txt", src.read_bytes(), "text/plain")}
+    r = client.post(
+        "/api/parse-835",
+        params={"payer": "co_medicaid_835"},
+        files=files,
+        headers=JSON,
+    )
+    assert r.status_code == 200, r.text
+    body = client.get("/api/batches", headers=JSON).json()
+    assert body["total"] == 1
+    item = body["items"][0]
+    assert item["kind"] == "835"
+    assert item["claimIds"] == []
+
+
 # --------------------------------------------------------------------------- #
 # /api/batches/{id}
 # --------------------------------------------------------------------------- #