[Research] Orchestration framework upgrade plan

[jerry609]

Source TODO

• 评估 LangGraph / CrewAI / AutoGen
• 统一 Agent 抽象层
• 可观测性增强

Scope

• Benchmark matrix and migration recommendation
• RFC for unified agent interface

Acceptance Criteria

• Decision doc with measurable tradeoffs and migration steps

[jerry609]

Delivered RFC with benchmark matrix, migration recommendation, and measurable rollout criteria: docs/ORCHESTRATION_UPGRADE_RFC.md