feat(ai): Day 3 — GetHealthInsightsTool + 配额前置检查 + Token 预算限制

- 新增 GetHealthInsightsTool：聚合档案摘要+化验异常+体征异常，输出 InsightCard
- 注册到 Patient/MedicalStaff 沙箱（10 个 Tool 全部就位）
- chat_handler 添加 QuotaService 配额前置检查（月度 Token/患者日限额）
- AgentRunParams 新增 token_budget 字段，Orchestrator 每轮累计检查超预算强制结束

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

@@ -2,6 +2,7 @@
 
 pub mod analyze_health_trends;
 pub mod analyze_lab_report;
+pub mod get_health_insights;
 pub mod query_appointments;
 pub mod query_lab_reports;
 pub mod query_medications;
@@ -11,6 +12,7 @@ pub mod search_medical_knowledge;
 
 pub use analyze_health_trends::AnalyzeHealthTrendsTool;
 pub use analyze_lab_report::AnalyzeLabReportTool;
+pub use get_health_insights::GetHealthInsightsTool;
 pub use query_appointments::QueryAppointmentsTool;
 pub use query_lab_reports::QueryLabReportsTool;
 pub use query_medications::QueryMedicationsTool;