refactor: 架构重组 — doc/bot → core/infra，新增 Agent 调度模块

- src/doc/ 拆分为 src/core/extraction/, matching/, validation/（核心业务逻辑）
- src/bot/ 重命名为 src/infra/browser/（浏览器自动化基础设施）
- fill_consumable_doc.py → src/infra/documents/consumable.py
- 新增 Agent 调度模块：coordinator.py, events.py, session.py，重构 orchestrator.py
- 更新 AGENTS.md、README.md 及所有子目录 README

scripts/test_multimodal.py

@@ -15,8 +15,8 @@ sys.stdout = io.TextIOWrapper(sys.stdout.buffer, encoding="utf-8", errors="repla
 ROOT = Path(__file__).resolve().parent.parent
 sys.path.insert(0, str(ROOT))  # noqa: E402
 
-from src.doc.llm_extractor import extract_document  # noqa: E402
-from src.doc.pdf import render_pdf_to_images  # noqa: E402
+from src.core.extraction import extract_document  # noqa: E402
+from src.infra.documents.pdf import render_pdf_to_images  # noqa: E402
 
 
 def test_render() -> None: