feat(views): anonymous daily view counter with social-proof badge

- New table symbol_views_daily(code, view_date, views) via migration 004.
- POST /api/views/{code} UPSERTs and returns today_views; GET returns
  today + last_7d + trend (last 7 days).
- Client dedupes via localStorage (views:logged map keyed by KST date) so a
  given browser counts once per day per code; refresh/extra tabs don't inflate.
- PriceHero shows "오늘 N명이 봤어요" pill when viewsToday > 0.

Read-only social proof — Toss 의 종목 상세에서 익명 카운트로 진입 신호를 주는 패턴.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

web/components/PriceHero.tsx

@@ -15,9 +15,20 @@ type Props = {
   asOf?: string | null;
   // 헤더 우측 sparkline 용 종가 시계열 (오래된 → 최신 순). 비어 있으면 미표시.
   series?: number[];
+  // social-proof — "오늘 N명이 봤어요" 배지. null/0 이면 숨김.
+  viewsToday?: number | null;
 };
 
-export function PriceHero({ name, code, market, current, prev, asOf, series }: Props) {
+export function PriceHero({
+  name,
+  code,
+  market,
+  current,
+  prev,
+  asOf,
+  series,
+  viewsToday,
+}: Props) {
   const change = current != null && prev != null ? current - prev : null;
   const pct = change != null && prev ? (change / prev) * 100 : null;
   const tone =
@@ -49,7 +60,17 @@ export function PriceHero({ name, code, market, current, prev, asOf, series }: P
             </span>
           )}
         </div>
-        {asOf && <div className="mt-1 text-xs text-zinc-500">기준 {asOf}</div>}
+        <div className="mt-1 flex items-center gap-2 text-xs text-zinc-500">
+          {asOf && <span>기준 {asOf}</span>}
+          {viewsToday != null && viewsToday > 0 && (
+            <span className="rounded-full border border-zinc-700/70 bg-zinc-900/60 px-2 py-0.5 text-[11px] text-zinc-300">
+              오늘 <span className="tabular-nums text-zinc-100">
+                {viewsToday.toLocaleString()}
+              </span>
+              명이 봤어요
+            </span>
+          )}
+        </div>
       </div>
 
       {series && series.length >= 2 && (