Async Hook Stderr Capture

What: Async hooks now capture and track stderr output separately from stdout, providing better visibility into hook errors and warnings.

Details:

• Hook state now includes dedicated stderr field initialized as empty string
• New function $wA() at line 72330 adds stderr to async hook process tracking
• Hook registration function CwA() at line 72298 initializes stderr field at line 72318
• Stderr stream is now monitored alongside stdout for background hook processes
• Evidence: Previously hooks only tracked stdout, now both stdout and stderr fields exist in hook state (line 72318)