bug: automatic allowance payment takes about 40 seconds after the request arrives #1614

Refs:

• feat: add allowances for automatic paykit payments #1340
• feat: accept allowance offers automatically on the allowee's wallet #1385 (review)

What happened?

On two regtest emulators, the payer's "Payment Executed" notification for a $2 automatic allowance payment appeared about 40 seconds after the payee sent the request, with the pending-request bell visible in the meantime.

The payer already receives private messages from linked contacts on every 10-second payment request poll, so the time is spent elsewhere. Candidates to measure:

• the payee's outgoing request waiting for its next full Paykit round (30 or 60 seconds) before it is sent;
• the request being deferred until the payee publishes a newer private payment list after the previous one was used;
• the Lightning payment and its settlement event.

Expected behavior

A request covered by an allowance is paid within a few seconds of arriving, and does not show in the pending-request bell while it is being paid.

Steps to Reproduce

1. Set and accept a $5 a payment, $50 a month allowance between two instances (set-and-accept.xml).
2. On the payee, send the payer a $2 Payment Request.
3. Time the payer's "Payment Executed" notification and watch the bell.

Bitkit Version

Unreleased: allowances branch of #1340.

Reproducibility

Seen once during review on two Android emulators; not yet timed against the logs.