feat(ai): Phase 3A RAG 知识库 — CRUD API + Agent Tool + 向量知识源 + 前端管理页

- 知识库 REST API: 10 个端点 (references/guides CRUD + re-embed)
- search_medical_knowledge Agent Tool: 语义检索参考资料和临床指南
- VectorKnowledgeSource: 实现 KnowledgeSource trait，自动降级
- 沙箱配置: Patient/MedicalStaff 允许使用知识库检索
- 前端 AiKnowledgePage: Tabs(参考资料/临床指南) + Table + Modal CRUD
- 权限码 seed 迁移: ai.knowledge.list + ai.knowledge.manage + 菜单

crates/erp-ai/src/agent/tools/mod.rs

@@ -4,8 +4,10 @@ pub mod query_appointments;
 pub mod query_lab_reports;
 pub mod query_medications;
 pub mod query_vitals;
+pub mod search_medical_knowledge;
 
 pub use query_appointments::QueryAppointmentsTool;
 pub use query_lab_reports::QueryLabReportsTool;
 pub use query_medications::QueryMedicationsTool;
 pub use query_vitals::QueryPatientVitalsTool;
+pub use search_medical_knowledge::SearchMedicalKnowledgeTool;