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- Delete superseded plan docs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/src/core/agentscope/runtime/runner.py

@@ -88,10 +88,7 @@ class AgentScopeRunner:
         owner_id = UUID(user_context.id)
         runtime_client_time = self._resolve_runtime_client_time(run_input=run_input)
         pipeline_spec = build_default_pipeline_spec(mode=system_agent_mode)
-        stage_agent_types = [
-            self._parse_agent_type(stage_name=stage.stage_name)
-            for stage in pipeline_spec.stages
-        ]
+        stage_agent_types = [stage.agent_type for stage in pipeline_spec.stages]
 
         async with AsyncSessionLocal() as session:
             if stage_agent_types == [AgentType.ROUTER, AgentType.WORKER]:
@@ -177,17 +174,6 @@ class AgentScopeRunner:
             enabled_tool_names=enabled_tool_names,
         )
 
-    @staticmethod
-    def _parse_agent_type(*, stage_name: str) -> AgentType:
-        normalized = stage_name.strip().lower()
-        if normalized == AgentType.ROUTER.value:
-            return AgentType.ROUTER
-        if normalized == AgentType.WORKER.value:
-            return AgentType.WORKER
-        if normalized == AgentType.MEMORY.value:
-            return AgentType.MEMORY
-        raise ValueError(f"unsupported stage name: {stage_name}")
-
     async def _load_stage_config(
         self,
         *,
@@ -355,7 +341,6 @@ class AgentScopeRunner:
             temperature=0.7,
             max_tokens=None,
             timeout_seconds=30,
-            visibility_consumer_bit=18,
             context_messages=ContextMessagesConfig(
                 mode=(
                     ContextBuildStrategy.DAY