Fix verifier counter leak during stale queue cleanup

[MoneroOcean]

Motivation

• The age-based verifier queue cleanup removed expired pending verification tasks without decrementing miner_address_verify, which could let attackers leak per-address pending counts and suppress future verifications for a victim payout address.

Description

• Decrement miner_address_verify when an expired pending task is removed during the verify queue cleanup in lib/coins/index.js, preserving the existing behavior of calling the task callback with null.
• This is implemented as a single-line insertion to balance the per-address in-flight counter for tasks that never reach worker start.

Testing

• No automated tests were executed as part of this rollout.
• The patch was validated by inspecting the git diff for lib/coins/index.js and committing the change successfully.

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Codex Task