character-picker-integration

Maintain the character picker, character registry, and local job queue tier added to AI-Assistant. Use when: editing storage/character_db/ data files; modifying core/character_registry.py or core/job_queue.py; changing /api/characters/* or /api/jobs/* routes; touching the character-picker.js / job-queue-panel.js frontend modules; integrating character_key into a new image-gen flow; or extending the queue lifecycle with new states.