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/lib/auth-client.ts

@@ -0,0 +1,15 @@
+import { createAuthClient } from 'better-auth/react'
+import { adminClient, emailOTPClient, lastLoginMethodClient } from 'better-auth/client/plugins'
+import { passkeyClient } from '@better-auth/passkey/client'
+
+export const authClient = createAuthClient({
+    baseURL: process.env.NEXT_PUBLIC_SITE_URL || "https://localhost:3000",
+    plugins: [
+        emailOTPClient(),
+        passkeyClient(),
+        lastLoginMethodClient(),
+        adminClient()
+    ]
+})
+
+export const { signIn, signOut, signUp, getSession, useSession } = authClient