fix(smtp): bound outbound delivery timeouts

[hacimertgokhan]

Summary

• Bound outbound SMTP endpoint/start and message transaction timeouts so slow MX hosts cannot occupy worker threads indefinitely.
• Abort timed-out SMTP sockets instead of sending cleanup commands over potentially stuck connections.
• Recover stale queued-message locks quickly so crashed or hung deliveries do not starve the queue.

Testing

• Syntax checked changed Ruby files with Docker Ruby 3.3 Alpine.
• Full RSpec was not run because local Ruby/Bundler is unavailable in this workspace.

[hacimertgokhan]

[github-actions]

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