ic402 v2.17.4

Patch — a refund the ledger rejects no longer strands the remainder behind a controller.
Reported by EngramX. No API, type, PaymentResult or example.did change.

Fixed

• A rejected refund left an ICP session resting in #closing. 2.17.3 handled a rejected settle
  and a refund the ledger refused, but not a refund the ledger rejected (for example while it is
  being upgraded): the close threw, the session rested in #closing with the remainder in escrow,
  and since 2.17.3's recoverEscrow refuses #closing, only a controller's forceResolveSession
  could free it. An ICRC ledger either answers or traps (rolling the transfer back), so a reject
  means nothing moved: it is now handled like a refused refund. The session ends #closed,
  lastActivityAt is refreshed, the payer can recover the remainder with recoverEscrow for the
  full 24 h, and the close returns #settlementFailed("Refund leg rejected (session marked #closed): …").
• A failed refund now releases the payer's daily reservation, refused or rejected, like every
  other terminal close. Before, a refused refund left the unspent remainder counted against the
  payer's daily limit until the day rolled over (a rejected one released it only when a controller
  ran forceResolveSession). A forceResolveSession landing during the refund still releases it
  once, not twice.
• The refused-refund message drops its "settle succeeded" clause, which was false when nothing had
  been consumed: it is now "Refund leg failed (session marked #closed): …".

Not changed

• A trap after one of the close's awaits can still leave a session resting in #closing; its exit
  is still the controller's forceResolveSession.
• With no ICP ledger reject left that makes the close throw, the sweep's catch arm is now reached
  only by a rejected self-call or a trap; it is covered by review only.
• A refund that fails during the expiry sweep is still not reported: the timer discards the sweep's
  results. A rejected one used to show as a session resting in #closing (the sessions.closing
  count); it now ends #closed silently, as a refused one already did. Surfacing sweep failures is
  a follow-up.