refactor(admin): CRM을 apps/admin 독립 프로젝트로 분리

- apps/web에서 admin 라우트/가드/sidebar 링크 제거
- apps/admin: 독립 Next.js 앱 (포트 3001)
  - 자체 login/unauthorized/auth callback
  - admin-sidebar: Overview/Users/Subscriptions/Usage
  - requireAdmin() 가드: profile.role='admin' 체크
- monorepo workspace에 apps/admin 등록

apps/web/src/app/(app)/admin/page.tsx

@@ -1,61 +0,0 @@
-// apps/web/src/app/(app)/admin/page.tsx
-// Admin CRM 대시보드 — 요약 카드 4개
-
-import { Box, Grid } from '@mui/material'
-import { MetalCard, PhosphorText } from '@d3ro/ui/components/ds'
-import { d3roPalette } from '@d3ro/ui/theme'
-import { getSupabaseServerClient } from '@/lib/supabase-server'
-
-interface StatCard {
-  label: string
-  value: string | number
-  color?: string
-}
-
-async function loadStats(): Promise<StatCard[]> {
-  const supabase = await getSupabaseServerClient()
-
-  const [profilesRes, paidRes, usageRes, expiringRes] = await Promise.all([
-    supabase.from('profiles').select('id', { count: 'exact', head: true }),
-    supabase.from('subscriptions').select('id', { count: 'exact', head: true })
-      .neq('tier', 'free').eq('status', 'active'),
-    supabase.from('daily_usage').select('count')
-      .eq('date', new Date().toISOString().split('T')[0]),
-    supabase.from('subscriptions').select('id', { count: 'exact', head: true })
-      .eq('status', 'active').eq('payment_provider', 'payple')
-      .lte('current_period_end', new Date(Date.now() + 7 * 86400000).toISOString()),
-  ])
-
-  const todayUsage = (usageRes.data as Array<{ count: number }> | null)
-    ?.reduce((sum, r) => sum + (r.count ?? 0), 0) ?? 0
-
-  return [
-    { label: 'TOTAL USERS', value: profilesRes.count ?? 0 },
-    { label: 'PAID SUBSCRIBERS', value: paidRes.count ?? 0, color: d3roPalette.tag.green },
-    { label: 'TODAY API CALLS', value: todayUsage, color: d3roPalette.accent.amber },
-    { label: 'EXPIRING (7D)', value: expiringRes.count ?? 0, color: d3roPalette.tag.red },
-  ]
-}
-
-export default async function AdminPage(): Promise<React.ReactElement> {
-  const stats = await loadStats()
-
-  return (
-    <Grid container spacing={2}>
-      {stats.map((stat) => (
-        <Grid size={{ xs: 12, sm: 6, md: 3 }} key={stat.label}>
-          <MetalCard>
-            <Box sx={{ textAlign: 'center', py: 2 }}>
-              <PhosphorText variant="label" sx={{ mb: 1, display: 'block', color: d3roPalette.text.label }}>
-                {stat.label}
-              </PhosphorText>
-              <PhosphorText variant="hero" sx={{ color: stat.color ?? d3roPalette.text.primary }}>
-                {stat.value}
-              </PhosphorText>
-            </Box>
-          </MetalCard>
-        </Grid>
-      ))}
-    </Grid>
-  )
-}