init: edu-content 内容库骨架（L1-L4 四层数据模型 + B类迁移 + lint/CI 工具）

sources/exams/cepoc.yaml

@@ -0,0 +1,30 @@
+sources:
+  - id: cepoc
+    title: CEPOC 剑桥英语机读完形填空题库（KET/PET/FCE）
+    publisher: Cambridge ALTA, University of Cambridge
+    type: dataset
+    url: https://github.com/CambridgeALTA/cepoc
+    license: cc-nc-education
+    license_note: "研究/教育用途，非商业（见仓库 licence.txt）"
+    fetch_method: git-clone
+    status: fetched
+    fetched_at: "2026-08-21"
+    items:
+      - id: cepoc-ket-json
+        title: KET.json（6套68空）
+        oss_key: edu-raw/exams/ket/questions/cepoc/KET.json
+        sha256: null
+        size: null
+        media_type: application/json
+        fetch_date: "2026-08-21"
+        status: planned
+        note: "latin1 编码；清洗为 qb-1.1 落 structured/exams/ket/questions/cepoc-a2-key.jsonl"
+      - id: cepoc-b1-json
+        title: B1 Preliminary.json（含 FCE 36套360空）
+        oss_key: edu-raw/exams/pet/questions/cepoc/B1-Preliminary.json
+        sha256: null
+        size: null
+        media_type: application/json
+        fetch_date: "2026-08-21"
+        status: planned
+        note: "清洗为 qb-1.1 落 structured/exams/pet/questions/cepoc-b1-preliminary.jsonl"