fix(network-monitor): move local proving off async runtime

[Ollie202]

Partially addresses #1976.

Problem

The network monitor still performs local transaction execution and proof generation directly from async code in two places:

• counter account deployment
• periodic counter increment submission

Both paths can run CPU-heavy VM/prover work without yielding, which can starve Tokio worker threads while the monitor is running.

Changes

• Move counter account deployment execution/proving into spawn_blocking_in_current_span.
• Move counter increment execution/proving into spawn_blocking_in_current_span.
• Add Clone for MonitorDataStore so the blocking task owns a fresh in-memory datastore and can rebuild its MAST store from the loaded accounts.
• Add a changelog entry for the Execution and signing is blocking in an async runtime #1976 follow-up.

Testing

• cargo +nightly fmt --check --all
• git diff --check

I also tried cargo check -p miden-network-monitor, but it stops before compiling on Windows because the current protocol dependency pulls an AggLayer submodule file with : in the filename:

tools/addRollupType/addRollupMainnet10/add_rollup_type_10_output-2025-03-11T15:54:21.263Z.json