map debug + coord backfill, remove email channel, countdown label

- Surface "X/Y passende Wohnungen mit Koordinaten" on the Karte view +
  admin-only "Koordinaten nachladen" button (POST /actions/backfill-coords)
  that geocodes missing flats via Google Maps directly from the web container
- Add googlemaps dep + GMAPS_API_KEY env to web service
- Light console.log in map.js ("rendering N/M markers", "building Leaflet…")
  so the browser DevTools shows what's happening
- Drop e-mail channel from notifications UI, notify dispatcher, and _alert_status;
  coerce legacy 'email' channel rows back to 'ui' on save
- Countdown said "Aktualisierung läuft…" next to "nächste Aktualisierung" →
  shortened to "aktualisiere…"

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

web/templates/_settings_notifications.html

@@ -11,7 +11,6 @@
         <select class="input" name="channel">
             <option value="ui"       {% if notifications.channel == 'ui' %}selected{% endif %}>Nur im Dashboard (kein Push)</option>
             <option value="telegram" {% if notifications.channel == 'telegram' %}selected{% endif %}>Telegram</option>
-            <option value="email"    {% if notifications.channel == 'email' %}selected{% endif %}>E-Mail</option>
         </select>
     </div>
 
@@ -26,12 +25,6 @@
         <input class="input" name="telegram_chat_id" value="{{ notifications.telegram_chat_id }}" placeholder="987654321">
     </div>
 
-    <div>
-        <label class="block text-xs uppercase text-slate-500 mb-1">E-Mail Adresse</label>
-        <input class="input" type="email" name="email_address" value="{{ notifications.email_address }}"
-               placeholder="du@example.com">
-    </div>
-
     <div class="border-t border-soft pt-4 space-y-2">
         <label class="flex items-center gap-2">
             <input type="checkbox" name="notify_on_match" {% if notifications.notify_on_match %}checked{% endif %}>