feat: add user preferences, agent name desensitization and related improvements
- Add user preferences persistence (model, migration, router, frontend core)
- Add agent name desensitization config
- Add agent_id to user custom prompts with migration
- Enhance agents persistence (base, memory, model, sql) and scheduler service
- Improve frontend agent cards/gallery, scheduled tasks, custom prompt menu
- Add pagination UI component; remove stale package-lock.json
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
