The interview-history feature already existed (interviews are recorded to each
platform's OASIS sqlite DB and `POST /api/simulation/interview/history` reads
them) but was broken on two fronts:
1. Backend crash: get_interview_history sorts merged twitter+reddit results by
"timestamp", but the two platforms store created_at with different types
(one int-like, one datetime string), raising
"'<' not supported between instances of 'int' and 'str'". Coerce the sort
key to str so mixed-type timestamps sort safely.
2. Step 5 (Interaction) never loaded that history, so past interviews vanished
on reload. Add getInterviewHistory() and load it on mount, seeding the
per-agent chat cache (chronological, prompt-prefix stripped, deduped across
platforms) so selecting an agent shows prior Q&A.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>