feat(admin-auth): add first-start onboarding flow and dev db reset command

apps/admin/src/app/register/page.tsx

@@ -0,0 +1,40 @@
+import { redirect } from "next/navigation"
+import { LoginForm } from "@/app/login/login-form"
+import { resolveRoleFromServerContext } from "@/lib/access-server"
+import { hasOwnerUser, isSelfRegistrationEnabled } from "@/lib/auth/server"
+
+export const dynamic = "force-dynamic"
+
+type SearchParams = Promise<Record<string, string | string[] | undefined>>
+
+function getSingleValue(input: string | string[] | undefined): string | undefined {
+  if (Array.isArray(input)) {
+    return input[0]
+  }
+
+  return input
+}
+
+export default async function RegisterPage({ searchParams }: { searchParams: SearchParams }) {
+  const params = await searchParams
+  const nextPath = getSingleValue(params.next) ?? "/"
+  const role = await resolveRoleFromServerContext()
+
+  if (role) {
+    redirect("/")
+  }
+
+  const hasOwner = await hasOwnerUser()
+
+  if (!hasOwner) {
+    redirect(`/welcome?next=${encodeURIComponent(nextPath)}`)
+  }
+
+  const enabled = await isSelfRegistrationEnabled()
+
+  if (!enabled) {
+    redirect(`/login?next=${encodeURIComponent(nextPath)}`)
+  }
+
+  return <LoginForm mode="signup-user" />
+}