Add session metrics logging for statesync server

[maxkozlovsky]

Added per-request logging of disk I/O statistics, upsert counts, and throughput metrics to enable performance monitoring and debugging of statesync server operations.

Fix the read counter in async io to use 64 bit, 32 bit was prone to overflow.

Add counter for number of bytes read in async io.

This code was generated using Claude Sonnet 4.5

[Copilot]

Pull Request Overview

This PR adds disk I/O and upsert metrics tracking to the state sync server to measure performance characteristics during request processing. The changes also include a test fix to ensure logs are properly flushed after a benchmark test.

Key changes:

• Added tracking of disk I/O operations and bytes read during state sync request handling
• Added tracking of upsert operations and bytes sent to clients
• Enhanced AsyncIO class to track total bytes read alongside existing read operation counts

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
category/async/io.hpp	Added bytes_read tracking field and accessor methods to AsyncIO class; updated size assertion
category/async/io.cpp	Modified account_read_ to accept and track buffer size for bytes read metric
category/statesync/statesync_server.cpp	Added comprehensive metrics collection and logging for disk I/O and upsert operations
category/statesync/test/test_statesync.cpp	Added quill::flush() call after benchmark test to ensure logs are written

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