arknet 0.2.0

arknet 0.2.0 adds native single-node MySQL and Redis clients and connection pools while remaining a C++20 header-only library.

• MySQL: queries, typed prepared statements, transactions, supported password authentication and verified TLS.
• Redis: binary-safe RESP2/RESP3 commands, pipelines, authentication, TLS/mTLS and separate push callbacks.
• Pools: exclusive leases, bounded acquisition queues and session reset before reuse.
• Request control: limits, deadlines, cancellation and explicit uncertain write outcomes; no automatic command replay.
• Dependencies: Boost.Asio and Boost.Beast are now the default. Standalone Asio supports TCP, UDP, RUDP, TLS and the database clients. Bundled BHO headers are removed.
• Runtime: orderly owned-runtime cleanup, safe listener metadata queries during shutdown, and MySQL resource ownership through asynchronous submission when callbacks destroy the connection.
• Documentation: bilingual examples, configuration, limits and local performance reports with SVG charts.

Migration and supported scope are covered in the release notes. MySQL requires OpenSSL and ARKNET_ENABLE_SSL. Database close operations are asynchronous; application callbacks must retain their required state. Local correctness and performance results do not establish production deployment capacity.