refactor(vault): Phase 3 — metadata convergence

- Backfill `created` frontmatter on 266 active notes (git date or mtime)
- Normalize `status` to 4 values: draft/active/done/archived (11 notes)
  - Active/进行中/needs-review → active
  - archive → archived
  - 待执行/conditional → draft
  - 完成/accepted → done
- Declare clipper boundary: 04_Archive/Inbox-Clippings/** exempt from migration
- Update depth rule: max 3 → max 4 levels (new notes only)
- Add metadata-converge.mjs script for reproducibility

02_Areas/Job/从零开始做 LLM 评测：每一步背后的道理.md

@@ -1,3 +1,6 @@
+---
+created: 2026-08-25
+---
 # 从零开始做 LLM 评测：每一步背后的道理
 
 **写给谁：** 有多年编程经验，但还没有做过大模型数据标注、模型评测、RAG 或 Agent 的人。