feat(bunny-cdn): refactor CDN hostname resolution and update asset URLs for improved flexibility

lib/bunny-cdn.ts

@@ -0,0 +1,20 @@
+function normalizeBunnyCdnHostname(raw: string | null | undefined): string | null {
+  if (!raw) return null;
+  const trimmed = raw.trim();
+  if (!trimmed) return null;
+
+  try {
+    const parsed = new URL(trimmed);
+    return parsed.hostname || null;
+  } catch {
+    return trimmed.replace(/^https?:\/\//, '').replace(/\/+$/, '') || null;
+  }
+}
+
+export function resolveServerBunnyCdnHostname(): string | null {
+  return normalizeBunnyCdnHostname(process.env.BUNNY_CDN_URL || process.env.NEXT_PUBLIC_BUNNY_CDN_URL);
+}
+
+export function resolvePublicBunnyCdnHostname(): string | null {
+  return normalizeBunnyCdnHostname(process.env.NEXT_PUBLIC_BUNNY_CDN_URL);
+}