feat: wire CMS redirects plugin into hooks.server.ts

New $lib/redirects.server.ts: lazy-loads GET /api/redirects, exact-match
index with trailing-slash normalisation, 60s TTL with background refresh
(cold start blocks once, subsequent requests get stale cache instantly).

hooks.server.ts: before legacy-redirect fallback, runs lookupRedirect for
GET requests. Editor-defined rules win over hardcoded /blog→/posts etc.
External targets (http://…) drop query; internal targets keep ?search.

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

src/hooks.server.ts

@@ -4,6 +4,7 @@ import { maintenanceResponse } from '$lib/maintenance.server';
 import { TRANSLATION_BUNDLE_SLUG } from '$lib/constants';
 import { env as envPublic } from '$env/dynamic/public';
 import { logWarn } from '$lib/log.server';
+import { lookupRedirect } from '$lib/redirects.server';
 import type { Handle } from '@sveltejs/kit';
 
 /**
@@ -62,6 +63,24 @@ export const handle: Handle = async ({ event, resolve }) => {
     return maintenanceResponse(200);
   }
 
+  // CMS-verwaltete Redirects (Admin UI → /admin/plugins/redirects).
+  // Editor-Regeln gewinnen gegen hardcoded Legacy-Patterns; nur GET, sonst
+  // brechen POST-Forms beim Pfadwechsel.
+  if (event.request.method === 'GET') {
+    const cmsRedirect = await lookupRedirect(event.url.pathname);
+    if (cmsRedirect) {
+      const search = event.url.search;
+      const dest =
+        cmsRedirect.to.startsWith('http') || !search
+          ? cmsRedirect.to
+          : `${cmsRedirect.to}${search}`;
+      return new Response(null, {
+        status: cmsRedirect.status,
+        headers: { location: dest },
+      });
+    }
+  }
+
   // Legacy-Pfade (/blog, /p) → /posts, /post. Vor Health-Check, weil
   // SvelteKit-Routing/CMS-Calls dafür unnötig.
   const redirectTo = legacyRedirectTarget(event.url.pathname);