feat(windkarte): Karten-UX Verbesserungen

- Polygon-Labels ab Zoom 13 mit zoom-proportionaler Schriftgröße
- Hover-Highlight, Deselect per Hintergrundklick
- Mobile Bottom-Sheet / Desktop Side-Panel (CSS-only)
- Share-Link via URL-Hash (#W-10), auto-select on load
- Share-Button + OSM-Link im Panel
- Reset-Button auf Karte
- Buffer-Spinner während Turf-Berechnung
- Leaflet-Attribution nach links (kollidierte mit Panel)
- fitBounds mit asymmetrischem Padding + maxZoom 14

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/lib/components/WindAreaPanel.svelte

@@ -5,9 +5,11 @@
 
   let {
     area,
+    center,
     onclose,
   }: {
     area: WindArea | null;
+    center: [number, number] | null;
     onclose: () => void;
   } = $props();
 
@@ -28,6 +30,22 @@
     if (s._slug) return `/post/${s._slug}`;
     return null;
   }
+
+  let copied = $state(false);
+  async function copyLink() {
+    await navigator.clipboard.writeText(location.href);
+    copied = true;
+    setTimeout(() => (copied = false), 2000);
+  }
+
+  $derived: osmHref: center
+    ? `https://www.openstreetmap.org/?mlat=${center[0].toFixed(5)}&mlon=${center[1].toFixed(5)}#map=14/${center[0].toFixed(5)}/${center[1].toFixed(5)}`
+    : null;
+
+  function osmHref(c: [number, number] | null): string | null {
+    if (!c) return null;
+    return `https://www.openstreetmap.org/?mlat=${c[0].toFixed(5)}&mlon=${c[1].toFixed(5)}#map=14/${c[0].toFixed(5)}/${c[1].toFixed(5)}`;
+  }
 </script>
 
 {#if area}
@@ -121,6 +139,28 @@
           Stellungnahme-Vorlage noch nicht verknüpft
         </div>
       {/if}
+
+      <!-- Actions -->
+      <div class="flex gap-2 pt-1">
+        <button
+          onclick={copyLink}
+          class="flex flex-1 items-center justify-center gap-1.5 rounded-lg border border-stein-200 px-2 py-2 text-xs font-medium text-stein-600 hover:bg-stein-50 transition-colors whitespace-nowrap"
+        >
+          <Icon icon={copied ? "mdi:check" : "mdi:link-variant"} class="size-3.5 shrink-0" />
+          {copied ? "Kopiert!" : "Link kopieren"}
+        </button>
+        {#if osmHref(center)}
+          <a
+            href={osmHref(center)}
+            target="_blank"
+            rel="noopener noreferrer"
+            class="flex flex-1 items-center justify-center gap-1.5 rounded-lg border border-stein-200 px-2 py-2 text-xs font-medium text-stein-600 hover:bg-stein-50 transition-colors whitespace-nowrap"
+          >
+            <Icon icon="mdi:map-outline" class="size-3.5 shrink-0" />
+            In OSM öffnen
+          </a>
+        {/if}
+      </div>
     </div>
   </div>
 {/if}