修复今日最高：新增 city_daily_max 表，所有数据源写入日最高

- DB: city_daily_max(icao,max_temp,obs_date,max_time) upsert
- AMOS/JMA/KNMI/FMI/HKO/METAR集群/CWA 采集后均写入
- Rust: 读 city_daily_max 获取准确日最高 + 时间
- 卡片恢复 High 行，显示最高温 + 达成时间
- new_high 提醒也基于真实日最高重新生效

Tested: cargo build + ruff check 均通过

monitoring-web/templates/monitor.html

@@ -43,6 +43,21 @@
   </div>
 
   <div class="card-meta">
+    <div class="meta-row">
+      <span class="label">High</span>
+      {% match c.today_max %}
+      {% when Some with (m) %}
+      <span class="value">{{ "{:.1}"|format(m) }}°C</span>
+      {% match c.max_time %}
+      {% when Some with (mt) %}
+      <span class="value max-time">{{ mt }}</span>
+      {% when None %}
+      {% endmatch %}
+      {% when None %}
+      <span class="value na">--</span>
+      {% endmatch %}
+      <span class="trend {{ c.trend.css_class() }}">{{ c.trend.symbol() }}</span>
+    </div>
     <div class="meta-row">
       <span class="label">Obs</span>
       {% match c.obs_age_min %}