feat(frontend): app shell + login + platform dashboard + billing tarifas

Primeiro commit do frontend Next.js (agente.md secao 161-176): login
split-brand, dashboard "Visão Geral da Plataforma" com instrumentos ao
vivo, e a tela Billing > Tarifas (price books + rate decks) completa —
listagem com busca/ordenacao, criacao com itens/entradas dinamicos via
Server Actions, detalhe — ponta a ponta contra a API real de billing
(fase 22).

Corrige de quebra 2 bugs reais achados construindo Tarifas: a topbar
tinha o titulo fixo "Visao Geral" em toda pagina, e a sidebar fixa de
256px nao tinha nenhuma versao mobile (conteudo espremido em ~130px) —
agora vira drawer via Radix Dialog abaixo de lg, com titulo/descricao da
topbar resolvidos dinamicamente por rota.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EWHKmcVJtstQFErbZ1AanY

apps/frontend/src/components/ui/input.tsx

@@ -0,0 +1,40 @@
+import * as React from "react";
+import { cn } from "@/lib/utils";
+
+export const Input = React.forwardRef<HTMLInputElement, React.InputHTMLAttributes<HTMLInputElement>>(
+  ({ className, ...props }, ref) => (
+    <input
+      ref={ref}
+      className={cn(
+        "h-9 w-full rounded-md border border-input bg-surface px-3 text-sm text-foreground outline-none ring-offset-background placeholder:text-muted-foreground focus-visible:ring-2 focus-visible:ring-ring disabled:cursor-not-allowed disabled:opacity-50",
+        className,
+      )}
+      {...props}
+    />
+  ),
+);
+Input.displayName = "Input";
+
+export const Select = React.forwardRef<HTMLSelectElement, React.SelectHTMLAttributes<HTMLSelectElement>>(
+  ({ className, children, ...props }, ref) => (
+    <select
+      ref={ref}
+      className={cn(
+        "h-9 w-full rounded-md border border-input bg-surface px-3 text-sm text-foreground outline-none ring-offset-background focus-visible:ring-2 focus-visible:ring-ring disabled:cursor-not-allowed disabled:opacity-50",
+        className,
+      )}
+      {...props}
+    >
+      {children}
+    </select>
+  ),
+);
+Select.displayName = "Select";
+
+export function FieldLabel({ children, htmlFor }: { children: React.ReactNode; htmlFor?: string }) {
+  return (
+    <label htmlFor={htmlFor} className="mb-1.5 block text-sm font-medium text-foreground">
+      {children}
+    </label>
+  );
+}