feat(termin): Termin-Detail unter /kalender/termin/<slug>, 302 von alt

Route /termin/[slug] -> /kalender/termin/[slug] verschoben, alte URL
302-redirect (QR-Codes/geteilte Links bleiben gueltig). Breadcrumb 3-stufig
(Start > Kalender > Titel). QR-/Detail-/OG-Links auf neuen Pfad.

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

src/lib/components/blocks/CalendarBlock.svelte

@@ -461,13 +461,13 @@
     }
 
     // QR-Code zum direkten Ausgeben/Scannen (Aushang, Infostand). Nutzt die
-    // canonical /termin/<slug>-URL (hat OG-Tags + Redirect), Fallback = Hash-
+    // canonical /kalender/termin/<slug>-URL (hat OG-Tags), Fallback = Hash-
     // Anchor im Kalender wenn kein Slug.
     let qrModal = $state<{ value: string; label: string } | null>(null);
 
     function openQr(item: EventCardItem) {
         const url = item._slug
-            ? `${window.location.origin}/termin/${encodeURIComponent(item._slug)}/`
+            ? `${window.location.origin}/kalender/termin/${encodeURIComponent(item._slug)}/`
             : `${window.location.origin}${window.location.pathname}#${eventId(item)}`;
         qrModal = { value: url, label: item.title || "Termin" };
     }
@@ -753,7 +753,7 @@
                             <div class="flex flex-wrap gap-2">
                                 {#if item._slug}
                                     <a
-                                        href={`/termin/${encodeURIComponent(item._slug)}/`}
+                                        href={`/kalender/termin/${encodeURIComponent(item._slug)}/`}
                                         class="btn-tertiary btn-sm"
                                     >
                                         Details

src/lib/components/blocks/EventDateBox.svelte

@@ -45,7 +45,7 @@
 <time
     datetime={isoDate(start)}
     aria-label={ariaLabel}
-    class="shrink-0 select-none aspect-square size-20 rounded-sm rounded-br-4xl bg-wald-200 text-wald-500 flex justify-center items-center shadow"
+    class="shrink-0 select-none aspect-square size-18 rounded-sm rounded-br-4xl bg-wald-200 text-wald-500 flex justify-center items-center shadow"
 >
     <div class="text-center font-black leading-normal">
         <div class="text-[10px] uppercase tracking-wider">