v1.3.2 — Prowlarr key fix + RomM 5.4 rescan

ROMarr v1.3.2 — the Prowlarr "Rejected the API key" bug fixed, and RomM 5.4 rescans work.

Indexer credential masking (#57, #60). Reported: add Prowlarr → Test ✓ → Save → Test again → "Rejected the API key". The key was never wrong. The indexer Save/Test routes merged credentials with the download-client merger, which has no spec for indexer types — so after Save the form's ******** mask was stored as the actual API key, and every later Test sent eight asterisks to Prowlarr. Now indexer routes merge against indexer secret fields, a placeholder with nothing stored is refused with a clear message, and torrentrss passkey no longer ships to the browser in clear text.

RomM 5.4 rescan (#58). RomM 5.4 refuses scan_library through the task runner, so post-import rescans silently stopped working. ROMarr now uses 5.4's POST /api/tasks/scan (narrowed to the imported platform), falls back to the task runner on older servers, and treats a 409 "scan already running" as deferred-not-failed with a bounded retry.

Suites: 2266 passed, 3 skipped (10 new secret-merge tests incl. HTTP-layer save→test round trip; 15 new RomM rescan tests).

If your Prowlarr indexer says "Rejected the API key" after updating: open it, retype the real key once, Save.