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

01_Projects/AI-Development/Obsidian Agent/refactor.md

@@ -1,7 +1,8 @@
 ---
+created: 2025-09-13
 title: Obsidian Agent Refactor
 date: 2026-01-10
-status: Active
+status: active
 ---
 
 # Obsidian Agent Refactor