Replaces deprecated ai_client.send() in _handle_request_event with
send_result() and branches on result.ok. On error, the first ErrorInfo
is routed to the event_queue as a 'response' with status='error',
allowing _on_comms_entry to add it to the discussion history.
The previous code called the @deprecated send() shim which silently
returns '' on error. The empty string was then filtered out by
_on_comms_entry (text_content.strip() check at line 3801), so users
saw no discussion entry for failed AI requests.
This also removes the dead 'except ai_client.ProviderError' clause at
line 3692 (the class was removed in commit 64b787b8). The 2 remaining
dead clauses at lines 305, 313 are fixed in the next commit (FR2).
ed
24ba249901