feat(ui): use timezone-aware time formatting across all templates

Replace hardcoded .Format() calls with FormatInTimezone() and
FormatTimestamptzInTimezone() helpers so all timestamps display in
the user's selected timezone.

Changes:
- book_detail.templ: remove incorrect templates. package prefix
- book_detail_modals.templ: add User param to ProgressSyncModal so
  timezone is available; convert Timestamp to FormatInTimezone()
- devices.templ: convert LastSync and LastSeen to FormatInTimezone()
- conflicts.templ: convert CreatedAt to FormatInTimezone()
- admin_users.templ: convert CreatedAt to FormatInTimezone() using
  currentUser.Timezone

Note: DatePublished is kept as a plain date format (MM-DD-YYYY) since
it is a pgtype.Date, not a timestamp, and does not need timezone
conversion.

templates/book_detail_modals.templ

@@ -6,7 +6,7 @@ import (
 )
 
 // ProgressSyncModal shows progress from all devices for manual review
-templ ProgressSyncModal(book handlers.MediaDetail) {
+templ ProgressSyncModal(user User, book handlers.MediaDetail) {
 	<div
 		id="progress-sync-modal"
 		class="hidden fixed inset-0 z-50 flex items-center justify-center overflow-y-auto"
@@ -65,7 +65,7 @@ templ ProgressSyncModal(book handlers.MediaDetail) {
 										{ source }
 									</span>
 									<p class="text-xs" style="color: var(--text-secondary);">
-										{ data.Timestamp.Format("01-02-2006 03:04 PM:05") }
+										{ FormatInTimezone(data.Timestamp, user.Timezone) }
 									</p>
 								</div>
 								<div class="text-right">