fix(learn): a chosen chip keeps its icon

The check Material draws on a chosen chip covered the icon of the rest
day's chip and of the card browser's status chips, as in Meditate. Their
colour says they are chosen, as in Explore's.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

apps/learn/halkyon_learn_flutter/lib/src/feature/card/widget/card_browser_sheets.dart

@@ -120,6 +120,7 @@ class _FilterSheetState() extends State<_FilterSheet> {
             children: [
               for (final status in CardStatus.values)
                 FilterChip(
+                  showCheckmark: false,
                   avatar: switch (status) {
                     CardStatus.reported => const Icon(
                       LucideIcons.flag,

apps/learn/halkyon_learn_flutter/lib/src/feature/home/widget/week_overview.dart

@@ -72,6 +72,7 @@ class const WeekOverview({
               Padding(
                 padding: const EdgeInsets.only(left: 8, right: 4),
                 child: FilterChip(
+                  showCheckmark: false,
                   avatar: const Icon(LucideIcons.snowflake, size: 16),
                   label: Text(l10n.weekRestDay),
                   selected: resting,