map view (Leaflet + OSM), iOS switches, Alarm → Benachrichtigungen

* flats: new lat/lng columns (migration v3); alert geocodes every new flat
  through googlemaps and ships coords in the payload
* web: CSP extended for unpkg (leaflet.css) + tile.openstreetmap.org
* Wohnungen tab: Liste/Karte view toggle (segmented, CSS-only via :has(),
  selection persisted in localStorage). Karte shows passende flats as Pins
  on an OSM tile map; Popup per Pin mit Adresse, Zimmer/m²/€ und Link
* Top-strip toggles are now proper iOS-style toggle switches (single
  rounded knob sliding in a pill, red when on), no descriptive subtitle
* Alarm-Karte verlinkt jetzt auf /einstellungen/benachrichtigungen
  (Filter-Karte bleibt /einstellungen/filter)

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

web/db.py

@@ -180,6 +180,11 @@ MIGRATIONS: list[str] = [
         value TEXT NOT NULL
     );
     """,
+    # 0003: lat/lng for map view
+    """
+    ALTER TABLE flats ADD COLUMN lat REAL;
+    ALTER TABLE flats ADD COLUMN lng REAL;
+    """,
 ]
 
 
@@ -388,8 +393,8 @@ def upsert_flat(payload: dict) -> bool:
             """INSERT INTO flats(
                 id, link, address, rooms, size, total_rent, sqm_price, year_built, wbs,
                 connectivity_morning_time, connectivity_night_time, address_link_gmaps,
-                payload_json, discovered_at
-            ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)""",
+                payload_json, discovered_at, lat, lng
+            ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)""",
             (
                 flat_id, payload.get("link", ""), payload.get("address", ""),
                 payload.get("rooms"), payload.get("size"), payload.get("total_rent"),
@@ -399,6 +404,7 @@ def upsert_flat(payload: dict) -> bool:
                 payload.get("address_link_gmaps"),
                 json.dumps(payload, default=str),
                 now_iso(),
+                payload.get("lat"), payload.get("lng"),
             ),
         )
         return True