Add agent_task_sessions table for per-task session state keyed by
(agent, adapter, taskKey). Add AgentTaskSession type, resetAgentSessionSchema
validator, and sessionDisplayId/sessionParamsJson to AgentRuntimeState.
Rework migration hash-resolution fallback ordering to prefer hash-based
matching over timestamp-based journal matching. Move backup-db.sh logic
into packages/db/src/backup.ts for programmatic use and simplify the shell
script to call the TypeScript implementation.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
