Closing a product leaves its SSO request live on the paired host

[decrypto21]

Closing a product leaves its SSO request live on the paired host

Follow-up to #263.

Problem

ProductRuntime::dispose() (truapi-server/src/host_core.rs:1551) aborts in-flight calls instead of cancelling them. The token never fires, so withdraw_request (pairing_host/sso_channel.rs:314) never runs and no SSO Cancel is sent. The phone keeps the prompt, and approving it still allocates or signs.

Reproduction

1. A pairing host stays up; a product connected to it calls resourceAllocation.request. The phone shows the sheet.
2. Kill the product process.
3. The phone receives nothing; the sheet stays up.

An explicit abort() on the same setup closes the sheet within about 1 s.

Fix

• The dispatcher fires every in-flight token with CancellationReason::Cancelled.
• dispose() calls that first, then aborts after AUTHORITY_CANCEL_UNWIND_GRACE.
• Test: dispose mid-SSO-call and assert a Cancel statement is submitted.

Related: #926, #933.