perf(cms-client+ssr): O(1)-Slug-Lookup, Sparse-Pages, höhere TTLs, Cache-Control, Parallel-Resolver

- getPageBySlug: neuer Filter-Lookup-Pfad (?slug=X&_fields=_slug) als
  primärer Fallback — O(1) statt komplette Page-Liste laden. Vollständige
  Liste nur noch als Last-Resort-Safety-Net. Skaliert egal wieviele Pages.
- getPages: Sparse-Projektion via _fields (8 Felder statt Voll-Resolve-
  Tree) → ~90 % kleinere Payload pro Call.
- CACHE_TTL hoch (Webhooks purgen eh): page/page_config/navigation/footer/
  fullwidth_banner/translation/openapi → 1h; tag/text_fragment → 30min;
  post → 10min. Spart Cold-Loads + CMS-Roundtrips.
- [...slug]/+page.server.ts: Cache-Control public, s-maxage=60,
  stale-while-revalidate=600 für öffentliche Pages (Caddy/Browser cachen).
  Preview-Branch bleibt private/no-store.
- Resolver parallelisiert: Calendar/Deadline/StellingnahmeGenerator
  starten sofort parallel zu PostOverview, nicht erst danach.
- Icon-Subset um clock-remove-outline ergänzt (Frist-abgelaufen-Banner).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/lib/iconify-mdi-subset.generated.json

@@ -117,6 +117,9 @@
     "clock-alert-outline": {
       "body": "<path fill=\"currentColor\" d=\"M11 7v6l5.2 3.1l.8-1.2l-4.5-2.7V7zm9 5v6h2v-6zm0 8v2h2v-2zm-2 0c-1.7 1.3-3.7 2-6 2c-5.5 0-10-4.5-10-10S6.5 2 12 2c4.8 0 8.9 3.4 9.8 8h-2.1c-.9-3.4-4-6-7.7-6c-4.4 0-8 3.6-8 8s3.6 8 8 8c2.4 0 4.5-1.1 6-2.7z\"/>"
     },
+    "clock-remove-outline": {
+      "body": "<path fill=\"currentColor\" d=\"M14.47 15.08L11 13V7h1.5v5.25l3.08 1.83c-.41.28-.79.62-1.11 1m-1.39 4.84c-.36.05-.71.08-1.08.08c-4.42 0-8-3.58-8-8s3.58-8 8-8s8 3.58 8 8c0 .37-.03.72-.08 1.08c.69.1 1.33.32 1.92.64c.1-.56.16-1.13.16-1.72c0-5.5-4.5-10-10-10S2 6.5 2 12s4.47 10 10 10c.59 0 1.16-.06 1.72-.16c-.32-.59-.54-1.23-.64-1.92m8.04-4.46L19 17.59l-2.12-2.12l-1.41 1.41L17.59 19l-2.12 2.12l1.41 1.42L19 20.41l2.12 2.13l1.42-1.42L20.41 19l2.13-2.12z\"/>"
+    },
     "content-save-outline": {
       "body": "<path fill=\"currentColor\" d=\"M17 3H5a2 2 0 0 0-2 2v14a2 2 0 0 0 2 2h14c1.1 0 2-.9 2-2V7zm2 16H5V5h11.17L19 7.83zm-7-7c-1.66 0-3 1.34-3 3s1.34 3 3 3s3-1.34 3-3s-1.34-3-3-3M6 6h9v4H6z\"/>"
     },