feat(orchestration): add orchestration system with task scheduling

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

backend/app/agents/orchestration/__init__.py

@@ -1,7 +1,16 @@
 """高级编排系统 - Phase 10"""
 
+from app.agents.orchestration.budget import build_subtask_budget
+from app.agents.orchestration.result_merge import merge_task_results
+from app.agents.orchestration.scheduler import (
+    ParallelExecutionScheduler,
+    build_subtask_specs,
+    ensure_child_links,
+)
+from app.agents.orchestration.subagent_runtime import subtask_spec_to_agent_task
 from app.agents.team.leader import TeamLeader, TeamTask, TaskStatus
 from app.agents.transport.remote import RemoteTransport, StructuredMessage
+from app.agents.orchestration.task_graph import build_bounded_task_graph, render_task_graph_summary
 from app.agents.background.manager import (
     BackgroundTaskManager,
     BackgroundTask,
@@ -14,7 +23,15 @@ __all__ = [
     "TaskStatus",
     "RemoteTransport",
     "StructuredMessage",
+    "ParallelExecutionScheduler",
+    "build_bounded_task_graph",
+    "build_subtask_budget",
+    "build_subtask_specs",
     "BackgroundTaskManager",
     "BackgroundTask",
+    "ensure_child_links",
     "get_background_task_manager",
+    "merge_task_results",
+    "render_task_graph_summary",
+    "subtask_spec_to_agent_task",
 ]