feat(brand): mavi/beyaz tema, yer tutucu logo, ikon üretimi ve PWA manifest

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/components/brand/logo.tsx

@@ -0,0 +1,27 @@
+import Image from "next/image";
+import { cn } from "@/lib/utils";
+import { tr } from "@/i18n/tr";
+
+/**
+ * Marka logosu: açık temada logo.svg, koyu temada logo-dark.svg (CSS ile seçilir,
+ * hydration uyumsuzluğu olmaz). Dosyalar public/brand/ altında.
+ */
+export function Logo({ className, priority }: { className?: string; priority?: boolean }) {
+  const common = { width: 120, height: 32, priority, unoptimized: true } as const;
+  return (
+    <span className={cn("inline-flex items-center", className)}>
+      <Image
+        src="/brand/logo.svg"
+        alt={tr.app.name}
+        className="h-8 w-auto dark:hidden"
+        {...common}
+      />
+      <Image
+        src="/brand/logo-dark.svg"
+        alt=""
+        className="hidden h-8 w-auto dark:block"
+        {...common}
+      />
+    </span>
+  );
+}