feat(api): /api/admin/survey GET — 목록 + 통계 + CSV export

- ?range=all|today|week 필터
- ?format=csv → BOM 포함 UTF-8 CSV 다운로드 (Excel 호환)
- 통계: 각 질문별 카운트 분포 + 만족도 평균 + 이메일률 + 완료시간 중간값
- admin HMAC cookie 인증 (verifyAdminTokenNode)

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

app/api/admin/survey/route.ts

@@ -0,0 +1,164 @@
+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);
+}
+
+interface SurveyRow {
+  id: string;
+  created_at: string;
+  age_range: string | null;
+  status: string | null;
+  awareness_freq: string | null;
+  tools_used: string[] | null;
+  tools_other: string | null;
+  cost_range: string | null;
+  best_tool: string | null;
+  best_satisfy: number | null;
+  free_opinion: string | null;
+  email: string | null;
+  user_agent: string | null;
+  referrer: string | null;
+  utm_source: string | null;
+  utm_medium: string | null;
+  utm_campaign: string | null;
+  completion_seconds: number | null;
+}
+
+export async function GET(request: Request) {
+  if (!(await checkAuth())) {
+    return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
+  }
+
+  const url = new URL(request.url);
+  const range = url.searchParams.get('range') ?? 'all';
+  const format = url.searchParams.get('format') ?? 'json';
+
+  const supabase = createAdminClient();
+  let query = supabase
+    .from('survey_responses')
+    .select('*')
+    .order('created_at', { ascending: false });
+
+  if (range === 'today') {
+    const today = new Date();
+    today.setHours(0, 0, 0, 0);
+    query = query.gte('created_at', today.toISOString());
+  } else if (range === 'week') {
+    const weekAgo = new Date(Date.now() - 7 * 24 * 60 * 60 * 1000);
+    query = query.gte('created_at', weekAgo.toISOString());
+  }
+
+  const { data, error } = await query;
+  if (error) {
+    return NextResponse.json({ error: error.message }, { status: 500 });
+  }
+
+  const rows: SurveyRow[] = (data ?? []) as SurveyRow[];
+
+  if (format === 'csv') {
+    const csv = toCsv(rows);
+    return new Response(csv, {
+      headers: {
+        'Content-Type': 'text/csv; charset=utf-8',
+        'Content-Disposition': `attachment; filename="contour-survey-${range}-${new Date().toISOString().slice(0, 10)}.csv"`,
+      },
+    });
+  }
+
+  return NextResponse.json({
+    total: rows.length,
+    stats: computeStats(rows),
+    responses: rows,
+  });
+}
+
+function toCsv(rows: SurveyRow[]): string {
+  if (rows.length === 0) return 'id,created_at\n';
+  const headers: (keyof SurveyRow)[] = [
+    'id',
+    'created_at',
+    'age_range',
+    'status',
+    'awareness_freq',
+    'tools_used',
+    'tools_other',
+    'cost_range',
+    'best_tool',
+    'best_satisfy',
+    'free_opinion',
+    'email',
+    'user_agent',
+    'referrer',
+    'utm_source',
+    'utm_medium',
+    'utm_campaign',
+    'completion_seconds',
+  ];
+  // BOM for Excel UTF-8 호환
+  const bom = '';
+  const lines = [headers.join(',')];
+  for (const r of rows) {
+    lines.push(
+      headers
+        .map((h) => {
+          const v = r[h];
+          if (v == null) return '';
+          if (Array.isArray(v)) return `"${v.join('|').replace(/"/g, '""')}"`;
+          return `"${String(v).replace(/"/g, '""').replace(/\r?\n/g, ' ')}"`;
+        })
+        .join(',')
+    );
+  }
+  return bom + lines.join('\n');
+}
+
+function counts(rows: SurveyRow[], key: keyof SurveyRow): Record<string, number> {
+  return rows.reduce((acc, r) => {
+    const v = r[key];
+    if (v != null && typeof v === 'string') {
+      acc[v] = (acc[v] ?? 0) + 1;
+    }
+    return acc;
+  }, {} as Record<string, number>);
+}
+
+function computeStats(rows: SurveyRow[]) {
+  const satisfyValues = rows
+    .map((r) => r.best_satisfy)
+    .filter((n): n is number => typeof n === 'number');
+  const satisfyAvg =
+    satisfyValues.length > 0
+      ? (satisfyValues.reduce((s, n) => s + n, 0) / satisfyValues.length).toFixed(2)
+      : '0';
+
+  const completionValues = rows
+    .map((r) => r.completion_seconds)
+    .filter((n): n is number => typeof n === 'number');
+  const completionMedian = median(completionValues);
+
+  return {
+    age_range: counts(rows, 'age_range'),
+    status: counts(rows, 'status'),
+    awareness_freq: counts(rows, 'awareness_freq'),
+    cost_range: counts(rows, 'cost_range'),
+    best_tool: counts(rows, 'best_tool'),
+    satisfy_avg: satisfyAvg,
+    email_rate: rows.length === 0 ? '0' : ((rows.filter((r) => r.email).length / rows.length) * 100).toFixed(1),
+    completion_seconds_median: completionMedian,
+  };
+}
+
+function median(arr: number[]): number {
+  if (arr.length === 0) return 0;
+  const sorted = [...arr].sort((a, b) => a - b);
+  const mid = Math.floor(sorted.length / 2);
+  return sorted.length % 2 ? sorted[mid] : Math.round((sorted[mid - 1] + sorted[mid]) / 2);
+}