Replace the CallerBackground isinstance branching in _summarize_ai_call
with direct reads from the new slim caller background dict
(emotional_register, situation, specific_details). Decouples CallRecord
population from caller_styles/caller_shapes so those fields can be
deleted in a later commit.
CallRecord schema preserved for backward-compat with existing
session_checkpoint.json. topic_category, emotional_state, energy_level
are now always empty strings (obsolete under slim architecture).
luke
effd52a95c