서버, 클라이언트, 서비스 워커 공용 코드를 lib/shared로 분리하고 브라우저 전용 모듈을 lib/client로 재구성

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/lib/client/media/exif.ts

@@ -0,0 +1,27 @@
+import ExifReader from "exifreader";
+
+export const extractExifDateTime = (fileBuffer: ArrayBuffer) => {
+  const exif = ExifReader.load(fileBuffer);
+  const dateTimeOriginal = exif["DateTimeOriginal"]?.description;
+  const offsetTimeOriginal = exif["OffsetTimeOriginal"]?.description;
+  if (!dateTimeOriginal) return undefined;
+
+  const [date, time] = dateTimeOriginal.split(" ");
+  if (!date || !time) return undefined;
+
+  const [year, month, day] = date.split(":").map(Number);
+  const [hour, minute, second] = time.split(":").map(Number);
+  if (!year || !month || !day || !hour || !minute || !second) return undefined;
+
+  if (!offsetTimeOriginal) {
+    // No timezone information.. Assume local timezone
+    return new Date(year, month - 1, day, hour, minute, second);
+  }
+
+  const offsetSign = offsetTimeOriginal[0] === "+" ? 1 : -1;
+  const [offsetHour, offsetMinute] = offsetTimeOriginal.slice(1).split(":").map(Number);
+
+  const utcDate = Date.UTC(year, month - 1, day, hour, minute, second);
+  const offsetMs = offsetSign * ((offsetHour ?? 0) * 60 + (offsetMinute ?? 0)) * 60 * 1000;
+  return new Date(utcDate - offsetMs);
+};