Net 685 assignment

[toschoosqd]

Summary

Implements the worker-side part of NET-685 behind the mvcc-chunks feature flag.

Workers now track when the current assignment has been fully applied and include last_applied_assignment_id in heartbeats once all required chunks are available and pending removals/downloads are complete.

Notes

• last_applied_assignment_id is an opaque String.
• Worker does not parse, compare, or order assignment IDs.
• Assignment ordering remains scheduler-owned under NET-686.
• While running, workers apply assignments in arrival order. If more than 5 assignments are queued, queued intermediate assignments are skipped and the worker advances to the newest pending assignment; the assignment currently being applied is never interrupted.
• The previously applied assignment intentionally remains reported while a newer assignment is still being applied.
• Requires the sqd-network proto change that adds last_applied_assignment_id to Heartbeat.

Validation

• cargo test -p sqd-worker storage::state

• cargo check -p sqd-worker

• cargo check -p sqd-worker --features mvcc-chunks --config 'patch."https://github.com/subsquid/sqd-network.git".sqd-messages.path="../sqd-network/crates/messages"'

• cargo test -p sqd-worker storage::state --features mvcc-chunks --config 'patch."https://github.com/subsquid/sqd-network.git".sqd-messages.path="../sqd-network/crates/messages"'

• cargo check -p sqd-worker --locked

• git diff --check