refactor(agent): restructure visibility masks, task queues, and memory service

Visibility mask refactoring:
- Replace dead UI_REALTIME bit with CONTEXT_ASSEMBLY (bit 1)
- Remove visibility_consumer_bit from SystemAgentLLMConfig and system_agents.yaml
- Simplify _resolve_user_message_visibility_mask: chat->UI_HISTORY|CONTEXT_ASSEMBLY, automation->0
- Simplify _resolve_stage_visibility_mask: memory->UI_HISTORY, router/worker->UI_HISTORY|CONTEXT_ASSEMBLY
- Remove stage_visibility_bit_map from store.py

Task queue renaming:
- Replace default_broker/bulk_broker/critical_broker with worker_agent_broker/worker_automation_broker
- Queue names: 'default'/'bulk'/'critical' -> 'agent'/'automation'
- Rename run_command_task -> run_command_task_agent/run_command_task_automation
- AgentService derives queue from runtime_mode: chat->agent, automation->automation

Architecture cleanup:
- Move context_service.py from runtime/ to agentscope/services/
- Add MemoryService in v1/memory/ following repository/service pattern
- Move consumer_registry.py and pipeline_spec.py from schemas/agent to agentscope/schemas/
- Delete dead code: registry_builder.py, VisibilityBitRef
- Delete superseded plan docs

docs/protocols/agent/api-endpoints.md

@@ -27,8 +27,7 @@ Base URL: `/api/v1/agent`
 
 - Body: `RunAgentInput`
 - 详细结构见 `docs/protocols/agent/run-agent-input.md`
-- `forwardedProps.agent_type` 必填，由调用方透传，task 不做默认赋值
-- `agent_type=memory` 仅用于自动化调度内部触发，API 入口返回 422
+- `forwardedProps.runtime_mode` 必填，值为 `"chat"` 或 `"automation"`
 
 ### Response
 
@@ -83,9 +82,9 @@ Base URL: `/api/v1/agent`
 
 当前阶段执行说明：
 
-- `worker` 模式采用两阶段：`router` -> `worker`。
-- `memory` 模式保持单阶段：`memory`。
-- 因此阶段事件可能出现 `router` / `worker` / `memory`。
+- `chat` 模式采用两阶段：`router` -> `worker`。
+- `automation` 模式由后端业务逻辑决定具体 Agent 类型。
+- 因此阶段事件可能出现 `router` / `worker`。
 
 ### 错误码