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

backend/data/case_loader.py

@@ -0,0 +1,105 @@
+"""
+Shared data-loading module for case data (outpatient + inpatient).
+
+Extracted from routers/cases.py so both cases and reports routers can use
+the same cached data without circular imports.
+"""
+
+import re
+import pandas as pd
+from pathlib import Path
+from datetime import datetime
+
+DATE_PATTERN = re.compile(r"^\d{4}-\d{2}-\d{2}$")
+
+# Data cache
+_cache = {
+    "outpatient": None,
+    "inpatient": None,
+    "loaded_at": None,
+}
+
+# Wuhan district mapping
+WUHAN_DISTRICTS = {
+    '江岸区': ['江岸'],
+    '江汉区': ['江汉'],
+    '武昌区': ['武昌'],
+    '洪山区': ['洪山'],
+    '汉阳区': ['汉阳'],
+    '东西湖区': ['东西湖'],
+    '黄陂区': ['黄陂'],
+    '硚口区': ['硚口'],
+    '江夏区': ['江夏'],
+    '青山区': ['青山'],
+    '新洲区': ['新洲'],
+    '蔡甸区': ['蔡甸'],
+    '东湖新技术开发区': ['东湖新技术开发区', '光谷'],
+    '经开（汉南）区': ['经开', '汉南', '经济开发区'],
+    '东湖生态旅游风景区': ['东湖生态旅游风景区']
+}
+
+PROJECT_ROOT = Path(__file__).parent.parent.parent
+DATA_DIR = PROJECT_ROOT / "Datas"
+
+
+def _extract_district(addr: str) -> str:
+    """Extract Wuhan district name from address string"""
+    if pd.isna(addr):
+        return '未知'
+    addr = str(addr)
+    for district, keywords in WUHAN_DISTRICTS.items():
+        for kw in keywords:
+            if kw in addr:
+                return district
+    return '其他'
+
+
+def load_data():
+    """Load and cache outpatient + inpatient data from Excel files"""
+    if _cache["loaded_at"] is not None:
+        return
+
+    try:
+        # Load outpatient data
+        df_out = pd.read_excel(DATA_DIR / "view_门诊.xlsx")
+        df_out['date'] = pd.to_datetime(df_out['门诊日期_re'])
+        df_out['district'] = df_out['现住址区'].fillna('未知')
+        _cache["outpatient"] = df_out
+
+        # Load inpatient data
+        df_in = pd.read_excel(DATA_DIR / "view_住院.xlsx")
+        df_in['date'] = pd.to_datetime(df_in['入院日期_re'])
+        df_in['district'] = df_in['现住址_脱敏'].apply(_extract_district)
+        _cache["inpatient"] = df_in
+
+        _cache["loaded_at"] = datetime.now()
+    except Exception as e:
+        raise RuntimeError(f"Data loading failed: {str(e)}")
+
+
+def get_combined_data():
+    """Return merged outpatient + inpatient data with unified diagnosis column"""
+    load_data()
+
+    df_out = _cache["outpatient"][['date', 'district', '初诊', '主诉']].copy()
+    df_out['type'] = 'outpatient'
+    df_out['diagnosis'] = df_out['初诊']
+
+    df_in = _cache["inpatient"][['date', 'district', '诊断名称']].copy()
+    df_in['type'] = 'inpatient'
+    df_in['diagnosis'] = df_in['诊断名称']
+    df_in['主诉'] = None
+
+    return pd.concat([df_out, df_in], ignore_index=True)
+
+
+def get_outpatient_data():
+    """Return the cached outpatient dataframe"""
+    load_data()
+    return _cache["outpatient"]
+
+
+def get_inpatient_data():
+    """Return the cached inpatient dataframe"""
+    load_data()
+    return _cache["inpatient"]