Remove the agent_orchestration enabled feature switch and root_delegates config; delegation edges now derive from the catalog's delegate_targets. Replace the four orchestration design/review docs with a single SUB_AGENT_DESIGN.md. Bump version to 1.13.0.
- drop agent_run_groups table and group_id/scope_kind/scope_id columns (schema v8)
- remove group_id from AgentExecutionContext and recovery group counters
- flatten TasksPage background tab into a per-run list
- add WebUI Agents page with definition CRUD and inline provider/model
- bump version to 1.11.0
