fix(ui): use timezone-aware formatting for Last Read timestamps in book detail and progress sync modal

Replace hardcoded 12-hour Format() calls with FormatTimestamptzInTimezone()
so that the Last Read time respects the user's selected timezone preference.
Both book_detail.templ and book_detail_modals.templ now use the same
timezone-aware helper that was introduced in the timezone support feature.

templates/book_detail.templ

@@ -250,7 +250,7 @@ templ BookDetail(user User, book handlers.MediaDetail, errorMessage string) {
 							if book.ReadingProgress.LastReadAt.Valid {
 								<div>
 									<p style="color: var(--text-secondary)">Last Read</p>
-									<p>{ book.ReadingProgress.LastReadAt.Time.Format("01-02-2006 03:04 PM") }</p>
+									<p>{ templates.FormatTimestamptzInTimezone(book.ReadingProgress.LastReadAt, user.Timezone) }</p>
 								</div>
 							}
 							if book.ReadingProgress.LastSyncSource.Valid {

templates/book_detail_modals.templ

@@ -110,7 +110,7 @@ templ ProgressSyncModal(book handlers.MediaDetail) {
 					}
 					if book.ReadingProgress.LastReadAt.Valid {
 						<p class="text-sm mt-2" style="color: var(--text-secondary);">
-							Last read: { book.ReadingProgress.LastReadAt.Time.Format("01-02-2006 03:04 PM") }
+							Last read: { FormatTimestamptzInTimezone(book.ReadingProgress.LastReadAt, user.Timezone) }
 						</p>
 					}
 				</div>