fix(sftp): swap inbound/outbound paths — FromHPE is inbound, ToHPE is outbound

The dzinesco SP9 seed had `paths.inbound` and `paths.outbound` mapped to
the wrong Gainwell MFT directories:

  - paths.outbound  was  FromHPE/   (HPE sends files FROM here TO us — inbound)
  - paths.inbound   was  ToHPE/     (we send files TO here — outbound)

So `/api/clearhouse/submit` was writing 837P claims to FromHPE (where
HPE puts acks/835s) and the SP16 scheduler was polling ToHPE (where our
claims go). 999 / TA1 / 835 files in the real FromHPE inbox were
unreachable.

Semantics per operator (2026-06-24):
  - FromHPE = HPE/Gainwell → us  = 999, TA1, 835  (inbound)
  - ToHPE   = us → HPE/Gainwell = 837P claims    (outbound)

**Runtime code (the actual fix):**
  - backend/src/cyclone/store.py            — SP9 seed paths flipped
  - backend/src/cyclone/edi/filenames.py    — docstring corrected

**Test fixtures + assertions (would otherwise fail on the new seed):**
  - backend/tests/test_clearhouse_api.py
  - backend/tests/test_providers_seed.py
  - backend/tests/test_sftp_stub.py        — incl. inbound dir paths
  - backend/tests/test_sftp_paramiko.py
  - backend/tests/test_store_update_clearhouse.py
  - backend/tests/test_api_clearhouse_patch.py
  - backend/tests/test_scheduler.py
  - backend/tests/test_api_scheduler.py

**Docs (text-only — keeps the codebase self-consistent):**
  - README.md
  - docs/reference/co-medicaid.md
  - docs/superpowers/specs/2026-06-20-cyclone-multi-payer-npi-sftp-design.md

**Operator action required after merge:** the existing clearhouse row in
`~/.local/share/cyclone/cyclone.db` was seeded with the old wrong
paths. Easiest recovery:
  1. `rm ~/.local/share/cyclone/cyclone.db` and let `ensure_clearhouse_seeded` re-run on next boot, OR
  2. PATCH /api/clearhouse with the new `paths` block (the SP25
     reconfigure hook picks it up live, including by the running scheduler).

**Verification:**
  - 82 tests in the affected files pass (test_clearhouse_api, test_providers_seed,
    test_sftp_stub, test_sftp_paramiko, test_store_update_clearhouse,
    test_api_clearhouse_patch, test_scheduler, test_api_scheduler, test_filenames).
  - Full backend suite: 1029 pass + 36 pre-existing order-dependent flakes
    unrelated to this change (verified by running the same tests in isolation).

README.md

@@ -690,7 +690,7 @@ backup create` manually retains full control.
 The `clearhouse.submit` endpoint uses `paramiko` to push a batch of
 generated 837 files to the dzinesco SFTP server
 (`mft.gainwelltechnologies.com:22`, path
-`/CO XIX/PROD/coxix_prod_11525703/FromHPE`). The SFTP credential is
+`/CO XIX/PROD/coxix_prod_11525703/ToHPE`). The SFTP credential is
 fetched from the macOS Keychain at call time — never read from YAML,
 never logged, never written to disk. The wire-up honors the file-naming
 template stored in the `clearhouse` config:
@@ -898,7 +898,7 @@ Shipped sub-projects (most recent first):
 - **Sub-project 13 (shipped) — SFTP wire-up.** `paramiko`-backed
   `SftpClient` replaces the SP9 stub. The clearhouse.submit endpoint
   actually pushes to
-  `mft.gainwelltechnologies.com:/CO XIX/PROD/coxix_prod_11525703/FromHPE`.
+  `mft.gainwelltechnologies.com:/CO XIX/PROD/coxix_prod_11525703/ToHPE`.
   SFTP credentials are read from the macOS Keychain at call time.
 - **Sub-project 12 (shipped) — Encryption at rest.** Optional
   SQLCipher AES-256 encryption of the SQLite file, with the key
@@ -1160,7 +1160,7 @@ the one-time setup recipe.
 
 - `POST /api/clearhouse/submit` — same endpoint as SP9; the
   implementation is now a real `paramiko` `SftpClient.write` to
-  `mft.gainwelltechnologies.com:/CO XIX/PROD/coxix_prod_11525703/FromHPE`.
+  `mft.gainwelltechnologies.com:/CO XIX/PROD/coxix_prod_11525703/ToHPE`.
   SFTP credentials are fetched from the macOS Keychain at call time.
 
 ## License