feat(sp33): cli resubmit-rejected-claims + fixture/test payer_id refresh

- Adds `cyclone resubmit-rejected-claims` to push corrected single-claim
  837 files to the Gainwell ToHPE SFTP dir. Idempotent (stat-then-skip by
  byte size). One persistent paramiko session per batch with
  reconnect-every=50 to dodge MOVEit's silent per-session file cap
  (~200 puts/session, no exception).
- Validates each file via `parse_837` before upload and rejects any
  whose payer_id is not `CO_TXIX` (catches a bad byte-fix early).
- Refreshes test fixtures (`minimal_837p.txt`, `co_medicaid_837p.txt`,
  `co_medicaid_837p_with_renderer.txt`) and the corresponding test
  assertions (`test_payer.py`, `test_payer_summary.py`,
  `test_co_medicaid_fixture.py`, `test_parse_837.py`) from the old
  `SKCO0`/`COHCPF` payer IDs to `CO_TXIX`, matching
  PayerConfig.co_medicaid() and the HCPF 837P Companion Guide.
- Adds `ingest/` to .gitignore — local scratch / production-data
  staging only.

backend/tests/test_parse_837.py

@@ -18,7 +18,7 @@ def test_parse_minimal_fixture_returns_one_claim():
     assert claim.subscriber.last_name == "Doe"
     assert claim.subscriber.first_name == "John"
     assert claim.subscriber.member_id == "ABC123"
-    assert claim.payer.id == "SKCO0"
+    assert claim.payer.id == "CO_TXIX"
     assert claim.claim.frequency_code == "1"
     assert claim.claim.place_of_service == "12"
     assert claim.claim.prior_auth == "PA123"