talents+chat: errored path reports back instead of redispatching
F5 errored redispatch caught in chat singleton — strengthens the
talent_errored contract so the chat singleton stops and reports the
failure to the owner instead of treating it as an implicit retry signal.
Both the inline follow-up message in chat_context and the
trigger-context Instruction line for talent_errored now read distinctly
from talent_finished. chat.md gains an explicit talent_errored bullet
in the Output Rules section.
F16's MAX_LOOP_RETRIES cap remains as the second line of defense.
Refreshes tests/baselines/api/sol/preview.json for the new chat.md
bullet (baseline tool also reserialized incidental em-dashes from
\u2014 to literal — ; semantically identical).
Refs req_tttxra67, req_kkhyi5wh.