Fix heap allocation leak in Socket.getValue

[ianegordon]

Summary

Socket.getValue allocates an UnsafeMutablePointer<O.SocketValue> that is never deallocated — on either the success or throw path — leaking one heap block on every socket-option read (socketType, receiveBufferSize, sendBufferSize, etc.).

The fix adds defer { valuePtr.deallocate() } immediately after allocation. This satisfies the documented precondition of UnsafeMutablePointer.deallocate(): the pointer is the start of the allocated block, and the memory is never initialized through Swift's typed model (getsockopt writes raw bytes; existing conformances use trivial Int32 values).

Testing

Full suite passes (449 tests, 51 suites). Existing SocketTests already cover correct value reads through getValue; the leak itself is not assertable in unit form.

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.89%. Comparing base (4e246d3) to head (48e68fa).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #226   +/-   ##
=======================================
  Coverage   92.88%   92.89%           
=======================================
  Files          71       71           
  Lines        3727     3728    +1     
=======================================
+ Hits         3462     3463    +1     
  Misses        265      265           

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