feat(termine): „Termin melden"-Link in Kalender + Footer-Sitemap

CalendarBlock: Termin-melden-Button in Action-Zeile.
Footer-Sitemap: link-termin-melden (CMS) → /termin-melden.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/lib/components/blocks/CalendarBlock.svelte

@@ -963,6 +963,13 @@
         <div
             class="flex flex-wrap items-center gap-2 px-4 py-2.5 border-b border-stein-200 bg-himmel-100"
         >
+            <a
+                href="/termin-melden"
+                class="btn-outline btn-sm inline-flex items-center gap-1.5 min-h-[36px]"
+            >
+                <Icon icon="lucide:plus" class="size-3.5 shrink-0" aria-hidden="true" />
+                Termin melden
+            </a>
             {#if isApplePlatform}
                 <a
                     href={webcalUrl}