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/contact/layout.tsx

@@ -0,0 +1,11 @@
+import type { Metadata } from "next"
+
+export const metadata: Metadata = {
+  title: "Contact & Report",
+  description: "Report issues, suggest features, or send feedback to the DeckyVault team.",
+  robots: { index: false, follow: true },
+}
+
+export default function ContactLayout({ children }: { children: React.ReactNode }) {
+  return children
+}