feat: add reports center, admin drill-down, disease filter + bug fixes + perf optimization

Frontend features:
- 报表中心 (ReportsCenter): list/detail views, diagnosis breakdown chart, CSV export
- 多级行政下钻 (AdminBreadcrumb): 湖北省→武汉市→区→街道 hierarchical drill-down
- 按病种筛选 (DiseaseFilter): multi-select diagnosis filter on monitoring + reports pages

Backend:
- Add /forecast/{days} endpoint, diagnosis filter params on cases endpoints
- Add /streets aggregation endpoint, enrich reports with real case data
- Extract shared case_loader module

Bug fixes (14):
- Fix missing /risk/forecast route (404), historyApi pointing to non-existent router
- Fix min_risk filter silently ignored in insights/hotspots
- Fix type mismatches: CaseTrendResponse, CaseStatsResponse shapes
- Fix silent .catch(() => {}) swallowing errors, fetchAlerts not clearing stale state
- Fix lru_cache caching exceptions, generateReport used cachedGet for write op
- Fix missing useEffect deps in Insights, DistrictComparison, ReportsCenter

Performance (9):
- Zustand selectors across 9 components (eliminate re-render cascades)
- Fix districtCases.sort() mutating store state, inline IIFE → memo'd component
- CaseLocationMap: React.memo, race protection, correct deps
- AlertCard: stable callbacks, TimelinePlayer: useMemo, TopNav: clock isolation
- SideNav: modules array to module scope, DiseaseFilter: memoized filter

frontend/src/stores/index.ts

@@ -1,7 +1,7 @@
 import { create } from 'zustand';
 import axios from 'axios';
 import type { GridRisk, GridDetail, Alert, Stats, ForecastDay } from '@/types';
-import { riskApi, alertApi, gridApi } from '@/services/api';
+import { riskApi, alertApi, gridApi, caseApi } from '@/services/api';
 
 function isCancelError(e: unknown): boolean {
   return axios.isCancel(e) || (e as Error)?.message === 'canceled';
@@ -84,7 +84,7 @@ export const useRiskStore = create<RiskState>((set, get) => ({
       set({ alerts: data.alerts || [] });
     } catch (e) {
       if (isCancelError(e)) return;
-      set({ error: (e as Error).message || '加载预警数据失败' });
+      set({ alerts: [], error: (e as Error).message || '加载预警数据失败' });
     }
   },
 
@@ -100,6 +100,8 @@ export const useRiskStore = create<RiskState>((set, get) => ({
 }));
 
 export { useAnalysisStore } from './analysisStore';
+export { useDrilldownStore } from './drilldownStore';
+export { useDiseaseStore } from './diseaseStore';
 
 
 interface TimelineState {
@@ -166,13 +168,11 @@ interface MonitoringState {
   gridFeatures: GridFeature[];
   aggregatedData: Array<{ date: string; district: string; total_cases: number; avg_AQI: number }>;
   districtCases: Array<{ district: string; total: number; outpatient: number; inpatient: number }>;
-  selectedDistrict: string | null;
   isLoading: boolean;
   error: string | null;
   fetchGridFeatures: (date: string) => Promise<void>;
   fetchAggregatedData: (startDate: string, endDate: string, district?: string) => Promise<void>;
-  fetchDistrictCases: () => Promise<void>;
-  setSelectedDistrict: (district: string | null) => void;
+  fetchDistrictCases: (diagnosis?: string) => Promise<void>;
   clearError: () => void;
 }
 
@@ -180,7 +180,6 @@ export const useMonitoringStore = create<MonitoringState>((set) => ({
   gridFeatures: [],
   aggregatedData: [],
   districtCases: [],
-  selectedDistrict: null,
   isLoading: false,
   error: null,
 
@@ -220,19 +219,17 @@ export const useMonitoringStore = create<MonitoringState>((set) => ({
     }
   },
 
-  fetchDistrictCases: async () => {
+  fetchDistrictCases: async (diagnosis) => {
     set({ isLoading: true, error: null });
     try {
-      const { caseApi } = await import('@/services/api');
-      const data = await caseApi.getDistricts();
-      set({ districtCases: data.districts || [], isLoading: false });
+      const data = await caseApi.getDistricts(diagnosis ? { diagnosis } : undefined);
+      const districts = Array.isArray(data) ? data : (data as any).districts || [];
+      set({ districtCases: districts, isLoading: false });
     } catch (e) {
       if (isCancelError(e)) return;
       set({ error: (e as Error).message || '加载区县病例数据失败', isLoading: false });
     }
   },
-
-  setSelectedDistrict: (district) => set({ selectedDistrict: district }),
 }));