docs: 文档重构 — 清理 AI agent 残留，整合 docs/ 目录结构

- 删除 11 个残留文件: continuation.md, init_plan.md, reasonix.toml, djapi/continuation.md, djapi/.serena/, djapi/.claude/, djapi/.mcp.json, .claude/skills/, docs/usage.html, docs/db_schema.md, docs/report_db_design.md
- 7 个 CLAUDE-*.md 移入 docs/ 并重命名去 CLAUDE- 前缀
- 新增 4 个文档: architecture.md, development.md, api.md, deployment.md
- 重写 usage.md, README.md
- 修复所有过时引用和交叉链接

djapi/api/report/serializers.py

@@ -14,6 +14,7 @@ class EventSerializer(serializers.Serializer):
     summary = serializers.CharField(allow_null=True)
     sentiment = serializers.CharField(allow_null=True)
     source = serializers.CharField(allow_null=True)
+    sources = serializers.JSONField(allow_null=True)
     url = serializers.CharField(allow_null=True)
 
 
@@ -47,4 +48,5 @@ class ImportantEventSerializer(serializers.Serializer):
     summary = serializers.CharField(allow_null=True)
     sentiment = serializers.CharField(allow_null=True)
     source = serializers.CharField(allow_null=True)
+    sources = serializers.JSONField(allow_null=True)
     url = serializers.CharField(allow_null=True)