content: regenerate Season 1 with a gentle onboarding difficulty curve

Generator: raise the early bot-win-rate floor to ~0.97 (near-guaranteed first
stages), widen the early move-buffer margin, and delay score-chase/line-sprint
objectives until stage 9/13 so the opening stretch is pure clear-a-gem. Result:
stage 1 now 16 moves (was 11), stages 1-9 all simple gems at 90-99% bot win.
Preserves theme.bgm=season_001; manifest SHA regenerated. Settings tag -> build 4.

lib/ui/screens/settings_screen.dart

@@ -79,7 +79,7 @@ class SettingsScreen extends ConsumerWidget {
               const SizedBox(height: 24),
               Center(
                 child: Text(
-                  'Block Seasons · v1.0.0 (build 3)',
+                  'Block Seasons · v1.0.0 (build 4)',
                   style: TextStyle(
                     color: Colors.white.withValues(alpha: 0.4),
                     fontSize: 12,