docs(14-03): complete semantic cache implementation plan

- Created SUMMARY.md with implementation details
- Updated STATE.md with new decisions and session info
- Updated ROADMAP.md progress (1/6 plans complete)
- Marked COST-02 requirement complete

Duration: 1 min (72s)
Tasks: 1 (TDD: RED → GREEN)
Tests: 11 passed

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

.planning/STATE.md

@@ -3,14 +3,14 @@ gsd_state_version: 1.0
 milestone: v1.4
 milestone_name: Zhihu Anti-Crawler
 status: executing
-stopped_at: Phase 14 context gathered
-last_updated: "2026-03-23T12:51:30.858Z"
+stopped_at: Completed 14-03-PLAN.md
+last_updated: "2026-03-23T14:36:46.811Z"
 last_activity: 2026-03-22 — Phase 13 Plan 07 completed (SRTProcessor integration)
 progress:
   total_phases: 15
   completed_phases: 11
-  total_plans: 38
-  completed_plans: 37
+  total_plans: 44
+  completed_plans: 38
   percent: 31
 ---
 
@@ -84,6 +84,9 @@ v1.6 Phase 13 decisions (from 13-CONTEXT.md):
 - [Phase 13]: Strategy Pattern with Protocol interface for extensibility (STRAT-01)
 - [Phase 13]: Unified segmentation strategy for all video types (per user decision, STRAT-02)
 - [Phase 13]: Strategy injection via constructor for easy testing and extension (STRAT-03)
+- [Phase 14-robustness-cost]: 缓存键使用 SHA256 内容哈希，确保相同内容精确匹配
+- [Phase 14-robustness-cost]: 缓存文件包含 version 字段（1.0），支持未来格式变更
+- [Phase 14-robustness-cost]: 缓存失败时返回 None，不中断主流程（错误容错）
 
 ### Technical Context
 
@@ -132,12 +135,13 @@ None.
 | 13 | 05 | 2min | 1 | 2 | 2026-03-22 |
 | 13 | 06 | 12min | 1 | 2 | 2026-03-22 |
 | 13 | 07 | 4min | 1 | 4 | 2026-03-22 |
+| Phase 14-robustness-cost P03 | 72 | 1 tasks | 3 files |
 
 ## Session Continuity
 
-Last session: 2026-03-23T12:51:30.856Z
-Stopped at: Phase 14 context gathered
-Resume file: .planning/phases/14-robustness-cost/14-CONTEXT.md
+Last session: 2026-03-23T14:36:46.809Z
+Stopped at: Completed 14-03-PLAN.md
+Resume file: None
 
 **Next step:** Phase 13 complete, continue to Phase 14 (鲁棒性) or Phase 15 (优化)