fix(miniprogram): 修复 API 接口字段对齐 — 33 接口端到端验证

P0: submitRecord() 路径修正 POST /follow-up-records → POST /follow-up-tasks/{id}/records
    + 请求体从 {task_id, content:{text}} 改为 {result, patient_condition, executed_date}
P1: ConsultationSession.subject/last_message 改为可选（后端暂不返回）
P1: Appointment.department 改为可选（后端未 JOIN 医生表）
P1: FollowUpRecord 结构对齐后端扁平字段（executed_date/result/medical_advice 等）
P2: Article 增加 status 可选字段

apps/miniprogram/src/services/consultation.ts

@@ -6,8 +6,8 @@ export interface ConsultationSession {
   doctor_id: string | null;
   consultation_type: string;
   status: string;
-  subject: string | null;
-  last_message: string | null;
+  subject?: string | null;
+  last_message?: string | null;
   last_message_at: string | null;
   unread_count_patient: number;
   created_at: string;