feat(calendar): compact variant for next-events teaser

Calendar block now supports variant: "default" | "compact".
- default = full calendar (unchanged)
- compact = next N events (default 3) + link to a target page

New CalendarCompactBlock.svelte: small card with month/day badge,
title, date/time/location line, "Alle kommenden Termine →" footer
link resolved from the schema's linkTo reference. Filters to future
events (12h tolerance for running ones).

BlockRenderer dispatches by block.variant inside the calendar case.
Schema (cms_content/_types/core/calendar.json5) adds variant + linkTo
+ limit fields.

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

src/lib/block-types.ts

@@ -420,6 +420,12 @@ export type CalendarBlockData = Omit<
   /** Slugs oder aufgelöste calendar_item-Einträge. */
   items?: (string | CalendarItemData)[];
   layout?: BlockLayout;
+  /** Variante: "default" voller Kalender, "compact" Anteaser. */
+  variant?: "default" | "compact";
+  /** Compact: Ziel-Page-Referenz hinter dem "Alle Termine"-Link. */
+  linkTo?: string | { _slug?: string;[key: string]: unknown };
+  /** Compact: Anzahl Termine (default 3). */
+  limit?: number;
 };
 
 /** Internal component block (_type: "internal_component"). */