feat(phase1): ad_channels 테이블 + admin CRUD API

- Migration: ad_channels table (uuid, name, url, status, memo)
- Routes: GET/POST /api/admin/ad-channels (list/create)
- Routes: PATCH/DELETE /api/admin/ad-channels/[id] (update/delete)
- Auth: admin_token verification via verifyAdminTokenNode
- RLS: service_role only, no additional policies

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

app/api/admin/ad-channels/[id]/route.ts

@@ -0,0 +1,47 @@
+import { NextResponse } from 'next/server';
+import { cookies } from 'next/headers';
+import { createAdminClient } from '@/lib/supabase/admin';
+import { verifyAdminTokenNode } from '@/lib/admin-auth';
+
+export const runtime = 'nodejs';
+
+async function checkAuth() {
+  const cookieStore = await cookies();
+  const token = cookieStore.get('admin_token')?.value;
+  return token && verifyAdminTokenNode(token);
+}
+
+export async function PATCH(request: Request, { params }: { params: Promise<{ id: string }> }) {
+  if (!(await checkAuth())) {
+    return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
+  }
+
+  const { id } = await params;
+  const body = await request.json();
+
+  const patch: Record<string, unknown> = { updated_at: new Date().toISOString() };
+
+  if (typeof body.name === 'string' && body.name.trim()) patch.name = body.name.trim();
+  if ('url' in body) patch.url = body.url?.trim() || null;
+  if ('memo' in body) patch.memo = body.memo?.trim() || null;
+  if (body.status === 'active' || body.status === 'paused') patch.status = body.status;
+
+  const supabase = createAdminClient();
+  const { error } = await supabase.from('ad_channels').update(patch).eq('id', id);
+
+  if (error) return NextResponse.json({ error: error.message }, { status: 500 });
+  return NextResponse.json({ success: true });
+}
+
+export async function DELETE(_request: Request, { params }: { params: Promise<{ id: string }> }) {
+  if (!(await checkAuth())) {
+    return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
+  }
+
+  const { id } = await params;
+  const supabase = createAdminClient();
+  const { error } = await supabase.from('ad_channels').delete().eq('id', id);
+
+  if (error) return NextResponse.json({ error: error.message }, { status: 500 });
+  return NextResponse.json({ success: true });
+}