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/conflicts.templ

@@ -111,7 +111,7 @@ templ Conflicts(user User, conflicts []handlers.ConflictDetailResponse, total in
 								</button>
 							</div>
 							<div class="text-sm" style="color: var(--text-secondary)">
-								Created: { conflict.CreatedAt.Format("01-02-2006 03:04:05 PM") }
+								Created: { FormatInTimezone(conflict.CreatedAt, user.Timezone) }
 								if conflict.ResolvedBy != "" {
 									| Resolved by: { conflict.ResolvedBy }
 								}