fix and enable agents window smoke tests (#317764)

* add logs

* fix _currentNewSession race in async send flows

Async commit-wait flows (_sendFirstChat, _sendFirstChatViaController,
_sendSubsequentChat) unconditionally cleared _currentNewSession on
completion. When a newer session was created while the previous one was
still awaiting commit, the clear stomped the newer session's pointer —
causing 'Session not found' errors on the next send.

Extract _clearCurrentNewSessionIfMatch() that only clears when the
value still points at the session that initiated the async flow.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* enable claude test

* update logging

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Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>