fix: journey map season-complete styling, scroll callback guard, palette constant

- Guard addPostFrameCallback with !_autoScrolled so it only fires once per
  widget lifetime instead of on every LayoutBuilder rebuild.
- Derive seasonComplete flag; pass it into _node so the last stage uses
  gold "done" styling (not "current/next") when the season is fully 3-starred.
- Extract const Color(0xFF232B4A) to GamePalette.lockedNode.
- Remove warnIfMissed: false from tap call in season_map_screen_test; ensureVisible
  already guarantees hit-testing succeeds (confirmed: test still passes cleanly).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/ui/screens/season_map_screen.dart

@@ -65,6 +65,8 @@ class _JourneyMapState extends ConsumerState<_JourneyMap> {
     final ids = [for (final stage in pack.stages) stage.id];
     final unlocked = repo.highestUnlockedIndex(pack.seasonId, ids);
     final totalStars = repo.totalStars(pack.seasonId);
+    final seasonComplete = totalStars == pack.stages.length * 3 &&
+        pack.stages.isNotEmpty;
     final locale = Localizations.localeOf(context).languageCode;
     final colors = ThemeColors(pack.theme);
 
@@ -78,9 +80,11 @@ class _JourneyMapState extends ConsumerState<_JourneyMap> {
             builder: (context, constraints) {
               final layout = MapLayout(width: constraints.maxWidth);
               final count = pack.stages.length;
-              WidgetsBinding.instance.addPostFrameCallback((_) =>
-                  _autoScrollTo(
-                      layout, unlocked, count, constraints.maxHeight));
+              if (!_autoScrolled) {
+                WidgetsBinding.instance.addPostFrameCallback((_) =>
+                    _autoScrollTo(
+                        layout, unlocked, count, constraints.maxHeight));
+              }
               return SingleChildScrollView(
                 controller: _scroll,
                 reverse: true,
@@ -104,6 +108,7 @@ class _JourneyMapState extends ConsumerState<_JourneyMap> {
                           unlocked,
                           repo.progressFor(pack.seasonId, ids[i])?.stars ?? 0,
                           colors,
+                          seasonComplete,
                         ),
                     ],
                   ),
@@ -166,9 +171,9 @@ class _JourneyMapState extends ConsumerState<_JourneyMap> {
   }
 
   Widget _node(BuildContext context, MapLayout layout, int i, int count,
-      int unlocked, int stars, ThemeColors colors) {
+      int unlocked, int stars, ThemeColors colors, bool seasonComplete) {
     final center = layout.nodeCenter(i, count);
-    final isCurrent = i == unlocked;
+    final isCurrent = i == unlocked && !seasonComplete;
     final isUnlocked = i <= unlocked;
     final size = isCurrent ? 64.0 : 52.0;
 
@@ -213,7 +218,7 @@ class _JourneyMapState extends ConsumerState<_JourneyMap> {
                               ],
                       )
                     : null,
-                color: isUnlocked ? null : const Color(0xFF232B4A),
+                color: isUnlocked ? null : GamePalette.lockedNode,
                 boxShadow: isCurrent
                     ? [
                         BoxShadow(

lib/ui/theme/palette.dart

@@ -22,6 +22,7 @@ class GamePalette {
 
   static Color tile(int colorId) => tileColors[colorId % tileColors.length];
 
+  static const lockedNode = Color(0xFF232B4A);
   static const gem = Color(0xFF7CF5FF);
   static const ghostLegal = Color(0x66FFFFFF);
   static const ghostIllegal = Color(0x55FF5252);