feat: 医生端Web后台 + SignalR实时问诊

- 新增 doctor_web/ React前端 (dashboard/患者/问诊/报告/随访)
- 后端新增 doctor_endpoints (14个医生API) + ConsultationHub (SignalR)
- Flutter端 SignalR 替换轮询实现实时聊天

doctor_web/src/components/layout/DoctorLayout.tsx

@@ -0,0 +1,70 @@
+import { NavLink, Outlet, useLocation } from 'react-router-dom';
+import { useEffect, useState } from 'react';
+import { api } from '../../services/api-client';
+import type { DashboardStats } from '../../types';
+import styles from './DoctorLayout.module.css';
+
+const NAV_ITEMS = [
+  { to: '/dashboard', label: '工作台', icon: '📊' },
+  { to: '/patients', label: '患者管理', icon: '👥' },
+  { to: '/consultations', label: '在线问诊', icon: '💬' },
+  { to: '/reports', label: '报告审核', icon: '📋' },
+  { to: '/follow-ups', label: '复查随访', icon: '📅' },
+];
+
+export default function DoctorLayout() {
+  const location = useLocation();
+  const [doctor, setDoctor] = useState<DashboardStats | null>(null);
+
+  useEffect(() => {
+    api.get<DashboardStats>('/api/doctor/dashboard').then(setDoctor).catch(() => {});
+  }, []);
+
+  return (
+    <div className={styles.layout}>
+      {/* 侧边栏 */}
+      <aside className={styles.sidebar}>
+        <div className={styles.brand}>
+          <div className={styles.brandTitle}>
+            <span>❤️</span> 健康管家
+          </div>
+          <div className={styles.brandSub}>医生工作台</div>
+        </div>
+
+        <nav className={styles.nav}>
+          {NAV_ITEMS.map(item => (
+            <NavLink
+              key={item.to}
+              to={item.to}
+              className={({ isActive }) =>
+                `${styles.navItem} ${isActive ? styles.active : ''}`
+              }
+            >
+              <span className={styles.navIcon}>{item.icon}</span>
+              {item.label}
+            </NavLink>
+          ))}
+        </nav>
+
+        <div className={styles.footer}>
+          <div className={styles.doctorInfo}>
+            <div className={styles.avatar}>
+              {doctor?.doctorName?.[0] ?? '王'}
+            </div>
+            <div>
+              <div className={styles.doctorName}>{doctor?.doctorName ?? '王建国'}</div>
+              <div className={styles.doctorMeta}>
+                {doctor?.doctorTitle ?? '主任医师'} · {doctor?.doctorDepartment ?? '心血管内科'}
+              </div>
+            </div>
+          </div>
+        </div>
+      </aside>
+
+      {/* 内容区 */}
+      <main className={styles.content} key={location.pathname}>
+        <Outlet />
+      </main>
+    </div>
+  );
+}