feat: show customer branding on login page

Adds public /v1/store/branding and /v1/store/logo endpoints so the
login page can display the customer's name and logo without auth,
with "Powered by LunarFront" underneath — matching the sidebar style.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/admin/src/routes/login.tsx

@@ -1,8 +1,13 @@
-import { useState } from 'react'
+import { useState, useEffect } from 'react'
 import { createFileRoute, useRouter, redirect } from '@tanstack/react-router'
 import { useAuthStore } from '@/stores/auth.store'
 import { login } from '@/api/auth'
 
+interface Branding {
+  name: string | null
+  hasLogo: boolean
+}
+
 export const Route = createFileRoute('/login')({
   beforeLoad: () => {
     const { token } = useAuthStore.getState()
@@ -20,6 +25,14 @@ function LoginPage() {
   const [password, setPassword] = useState('')
   const [error, setError] = useState('')
   const [loading, setLoading] = useState(false)
+  const [branding, setBranding] = useState<Branding | null>(null)
+
+  useEffect(() => {
+    fetch('/v1/store/branding')
+      .then((r) => r.ok ? r.json() : null)
+      .then((data) => { if (data) setBranding(data) })
+      .catch(() => {})
+  }, [])
 
   async function handleSubmit(e: React.FormEvent) {
     e.preventDefault()
@@ -48,8 +61,16 @@ function LoginPage() {
         style={{ backgroundColor: '#131c2e', borderColor: '#1e2d45' }}
       >
         <div className="text-center mb-8">
-          <h1 className="text-3xl font-bold" style={{ color: '#d8dfe9' }}>LunarFront</h1>
-          <p className="text-sm mt-1" style={{ color: '#6b7a8d' }}>Small Business Management</p>
+          {branding?.hasLogo ? (
+            <img src="/v1/store/logo" alt={branding.name ?? 'Store'} className="max-h-14 max-w-[220px] object-contain mx-auto" />
+          ) : (
+            <h1 className="text-3xl font-bold" style={{ color: '#d8dfe9' }}>{branding?.name ?? 'LunarFront'}</h1>
+          )}
+          {branding?.name ? (
+            <p className="text-[10px] mt-2" style={{ color: '#4a5568' }}>Powered by <span style={{ color: '#6b7a8d' }}>LunarFront</span></p>
+          ) : (
+            <p className="text-sm mt-1" style={{ color: '#6b7a8d' }}>Small Business Management</p>
+          )}
         </div>
         <form onSubmit={handleSubmit} className="space-y-4">
           <div className="space-y-2">