feat(mypage): 다운로드 버튼 활성화 (Phase 2) + status 분기

- packFiles state + /api/packs/list-mine fetch (RLS 우회 위해 admin client 라우트)
- handleDownload: /api/packs/sign-link 호출 → window.location 이동
- 카드: 자료 리스트 DB SSOT (PACK_ASSETS.files 폐기)
- order.status === 'completed' 만 다운로드 활성, 그 외는 Phase 1 placeholder 유지
- 4시간 만료 안내 추가

빌드 복구: B3에서 깨진 mypage 빌드를 이번 commit이 복구.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

app/api/packs/list-mine/route.ts

@@ -0,0 +1,40 @@
+import { NextResponse } from 'next/server';
+import { cookies } from 'next/headers';
+import { createServerClient as createSSRClient } from '@supabase/ssr';
+import { createAdminClient } from '@/lib/supabase/admin';
+import { extractPackTier, type PackTier } from '@/lib/pack-assets';
+import { tierIncludes, getPackFilesForTiers } from '@/lib/supabase/pack-files';
+
+export const runtime = 'nodejs';
+
+export async function GET() {
+  const cookieStore = await cookies();
+  const supabase = createSSRClient(
+    process.env.NEXT_PUBLIC_SUPABASE_URL!,
+    process.env.NEXT_PUBLIC_SUPABASE_ANON_KEY!,
+    {
+      cookies: {
+        getAll: () => cookieStore.getAll(),
+        setAll: () => {},
+      },
+    },
+  );
+  const { data: { user } } = await supabase.auth.getUser();
+  if (!user) return NextResponse.json({ files: [] });
+
+  const admin = createAdminClient();
+  const { data: orders } = await admin
+    .from('contact_requests')
+    .select('service, status')
+    .eq('user_id', user.id)
+    .eq('status', 'completed');
+
+  const tiers = new Set<PackTier>();
+  for (const o of (orders ?? [])) {
+    const t = extractPackTier(o.service);
+    if (t) tierIncludes(t).forEach((x) => tiers.add(x));
+  }
+
+  const files = await getPackFilesForTiers(admin, Array.from(tiers));
+  return NextResponse.json({ files });
+}