refactor: convert to bun workspaces monorepo

- Move web app into apps/web/
- Create packages/shared/ with shared types
- Create plugins/decky-vault/ scaffold
- Root package.json manages workspaces only

apps/web/app/profile/layout.tsx

@@ -0,0 +1,12 @@
+import type { Metadata } from "next"
+
+export const metadata: Metadata = {
+    title: "Profile",
+    description:
+        "Your DeckyVault profile — saved games, benchmark contributions, and performance history.",
+    robots: { index: false, follow: false },
+}
+
+export default function ProfileLayout({ children }: { children: React.ReactNode }) {
+    return children
+}