Weather: show city name above the current conditions, toggleable

Just the city itself (first segment of the geocode label), not the
full "City, State, Country" string -- too cluttered for a dashboard
header. Off by default for manually-entered coordinates since there's
no resolved place name to show there regardless of the toggle.
New show_city setting, on by default, alongside the other display
toggles in Weather settings.

web/templates/settings_weather.html

@@ -35,6 +35,10 @@
       <p class="hint">Weather itself only refreshes the panel when something actually changed, so a shorter interval here mostly just means fresher data, not more flashing.</p>
     </div>
     <div class="field">
+      <label class="checkbox">
+        <input type="checkbox" name="show_city" {{ "checked" if settings.show_city != False }}>
+        City name
+      </label>
       <label class="checkbox">
         <input type="checkbox" name="show_hourly_graph" {{ "checked" if settings.show_hourly_graph != False }}>
         Hourly temperature graph