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- Delete superseded plan docs

backend/tests/unit/core/taskiq/test_app.py

@@ -5,14 +5,13 @@ import sys
 
 import pytest
 
-from core.taskiq.app import broker, bulk_broker, critical_broker, default_broker
+from core.taskiq.app import broker, worker_agent_broker, worker_automation_broker
 
 
 def test_taskiq_broker_is_configured() -> None:
     assert broker is not None
-    assert default_broker is broker
-    assert critical_broker is not None
-    assert bulk_broker is not None
+    assert worker_agent_broker is broker
+    assert worker_automation_broker is not None
 
 
 def test_taskiq_app_configures_logging_on_import(