docs(01-01): complete WorkflowStateManager plan

Summary:
- WorkflowStateManager with atomic write and backup rotation
- 90% test coverage (20 tests)
- 5 min execution time

State updates:
- Plan counter advanced to 3
- Progress: 67% (2/3 plans complete)
- Requirements marked complete: PIPE-02, REL-01

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.planning/REQUIREMENTS.md

@@ -10,12 +10,12 @@ Requirements for initial release. Each maps to roadmap phases.
 ### Pipeline Model (管道模型)
 
 - [x] **PIPE-01**: 统一的管道模型 - 每个步骤是独立管道，定义清晰的输入→处理→输出
-- [ ] **PIPE-02**: 步骤级状态管理 - 主要步骤完成后记录状态到 workflow_state.json，支持断点续传
+- [x] **PIPE-02**: 步骤级状态管理 - 主要步骤完成后记录状态到 workflow_state.json，支持断点续传
 - [x] **PIPE-03**: 统一 JSON Schema - 所有子技能遵守统一的 StepInput/StepOutput 格式规范
 
 ### Reliability (可靠性)
 
-- [ ] **REL-01**: 幂等执行保证 - 重复执行同一链接不会产生重复文件或重复处理
+- [x] **REL-01**: 幂等执行保证 - 重复执行同一链接不会产生重复文件或重复处理
 - [ ] **REL-02**: 错误恢复策略 - 403/超时/网络错误有明确的降级策略和重试机制
 - [x] **REL-03**: 清晰的流程定义 - 每个步骤的前置条件、输出格式、成功标准明确
 
@@ -70,9 +70,9 @@ Which phases cover which requirements. Updated during roadmap creation.
 | Requirement | Phase | Status |
 |-------------|-------|--------|
 | PIPE-01 | Phase 1 | Complete |
-| PIPE-02 | Phase 1 | Pending |
+| PIPE-02 | Phase 1 | Complete |
 | PIPE-03 | Phase 1 | Complete |
-| REL-01 | Phase 1 | Pending |
+| REL-01 | Phase 1 | Complete |
 | REL-02 | Phase 1 | Pending |
 | REL-03 | Phase 1 | Complete |
 | VAL-01 | Phase 1 | Complete |