niwaki v1.3.1

Fixed

• Subscription push silently never delivered. login()/_refresh_token()
  (sync and async) explicitly set the APIC-cookie cookie on the httpx
  client, on top of the cookie httpx already stores automatically from the
  APIC's own Set-Cookie response header. The explicit call didn't pin a
  domain, so it landed as a second, distinct jar entry (same name, empty
  domain) rather than overwriting the first. The APIC accepts the resulting
  malformed, duplicated Cookie: APIC-cookie=...; APIC-cookie=... header for
  ordinary reads/writes and even for the subscribe GET itself (a valid
  subscriptionId still comes back) — but it silently breaks the APIC's
  internal link between that request and the caller's already-open
  WebSocket, so no push ever arrives, and the subscribe response's initial
  imdata can come back empty even when matching objects exist. Fixed by
  pinning the cookie to the session's own host on every login()/
  _refresh_token() call, so it overwrites in place instead of duplicating.
  Only subscribe() was affected — every other read/write path was already
  correct, which is why this went unnoticed until a live subscription
  investigation traced the exact Cookie header sent on the wire.
  Re-validated live end to end on a freshly provisioned fabric: create,
  modify, delete, filtered subscriptions, forced reconnect, and refresh
  escalation all deliver correctly now.