feat: ship ad-supported only — gate Remove Ads IAP behind kIapEnabled=false

The developer is an individual without a Korean business registration, so
the App Store / Play paid-apps (merchant) agreements can't be completed.
Hide the Remove Ads + Restore tiles and skip IAP init; ads always show.
AdMob revenue is independent of those agreements. Reversible: flip
kIapEnabled to re-enable once a merchant agreement exists. Bump to build 2;
drop the now-unused IAP review-screenshot generator.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

lib/app.dart

@@ -2,6 +2,7 @@ import 'package:flutter/material.dart';
 import 'package:flutter_localizations/flutter_localizations.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 
+import 'core/feature_flags.dart';
 import 'l10n/gen/app_localizations.dart';
 import 'state/providers.dart';
 import 'ui/screens/splash_screen.dart';
@@ -24,7 +25,7 @@ class _BlockSeasonsAppState extends ConsumerState<BlockSeasonsApp>
       // Eagerly start the IAP service so its purchase stream is live for the
       // whole session — restores and interrupted/deferred transactions are
       // delivered (and completed) even if the player never opens Settings.
-      ref.read(iapServiceProvider);
+      if (kIapEnabled) ref.read(iapServiceProvider);
       // Start background music for the current context (menu by default).
       ref.read(musicServiceProvider).playKey(ref.read(activeThemeProvider).bgm);
     });

lib/core/feature_flags.dart

@@ -0,0 +1,13 @@
+/// Compile-time feature toggles.
+library;
+
+/// Whether the in-app purchase ("Remove Ads") is offered.
+///
+/// Disabled for launch: the developer is an individual without a Korean
+/// business registration, so the App Store / Play paid-apps (merchant)
+/// agreements can't be completed. The app ships ad-supported only. AdMob
+/// revenue is independent of those agreements, so ads still pay out.
+///
+/// To re-enable later (once a merchant agreement exists): flip this to `true`,
+/// re-activate the `remove_ads` product in both stores, and ship a new build.
+const bool kIapEnabled = false;

lib/ui/screens/settings_screen.dart

@@ -2,6 +2,7 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 
+import '../../core/feature_flags.dart';
 import '../../game/models/season.dart';
 import '../../l10n/gen/app_localizations.dart';
 import '../../state/providers.dart';
@@ -13,18 +14,8 @@ class SettingsScreen extends ConsumerWidget {
   @override
   Widget build(BuildContext context, WidgetRef ref) {
     final l10n = AppLocalizations.of(context)!;
-    final adsRemoved = ref.watch(adsRemovedProvider);
     final soundOn = ref.watch(soundEnabledProvider);
     final musicOn = ref.watch(musicEnabledProvider);
-    final iap = ref.read(iapServiceProvider);
-
-    ref.listen<bool>(adsRemovedProvider, (prev, next) {
-      if (next && !(prev ?? false)) {
-        ScaffoldMessenger.of(context).showSnackBar(
-          SnackBar(content: Text(l10n.adsRemovedThanks)),
-        );
-      }
-    });
 
     return Stack(
       fit: StackFit.expand,
@@ -51,31 +42,9 @@ class SettingsScreen extends ConsumerWidget {
                 onChanged: (v) =>
                     ref.read(musicEnabledProvider.notifier).set(v),
               ),
-              const Divider(),
-              ListTile(
-                title: Text(l10n.removeAds),
-                subtitle: Text(l10n.removeAdsDescription),
-                trailing: adsRemoved
-                    ? const Icon(Icons.check_circle, color: Colors.green)
-                    : Text(iap.product?.price ?? ''),
-                onTap: adsRemoved
-                    ? null
-                    : () async {
-                        if (!iap.available || iap.product == null) {
-                          ScaffoldMessenger.of(context).showSnackBar(
-                            SnackBar(content: Text(l10n.purchaseUnavailable)),
-                          );
-                          return;
-                        }
-                        await iap.buyRemoveAds();
-                      },
-              ),
-              const Divider(),
-              ListTile(
-                leading: const Icon(Icons.restore),
-                title: Text(l10n.restorePurchases),
-                onTap: () => iap.restorePurchases(),
-              ),
+              // The "Remove Ads" purchase is gated off at launch (no merchant
+              // agreement); the app ships ad-supported only. See kIapEnabled.
+              if (kIapEnabled) ..._iapTiles(context, ref, l10n),
               const SizedBox(height: 24),
               Center(
                 child: Text(
@@ -92,4 +61,46 @@ class SettingsScreen extends ConsumerWidget {
       ],
     );
   }
+
+  List<Widget> _iapTiles(
+      BuildContext context, WidgetRef ref, AppLocalizations l10n) {
+    final adsRemoved = ref.watch(adsRemovedProvider);
+    final iap = ref.read(iapServiceProvider);
+
+    ref.listen<bool>(adsRemovedProvider, (prev, next) {
+      if (next && !(prev ?? false)) {
+        ScaffoldMessenger.of(context).showSnackBar(
+          SnackBar(content: Text(l10n.adsRemovedThanks)),
+        );
+      }
+    });
+
+    return [
+      const Divider(),
+      ListTile(
+        title: Text(l10n.removeAds),
+        subtitle: Text(l10n.removeAdsDescription),
+        trailing: adsRemoved
+            ? const Icon(Icons.check_circle, color: Colors.green)
+            : Text(iap.product?.price ?? ''),
+        onTap: adsRemoved
+            ? null
+            : () async {
+                if (!iap.available || iap.product == null) {
+                  ScaffoldMessenger.of(context).showSnackBar(
+                    SnackBar(content: Text(l10n.purchaseUnavailable)),
+                  );
+                  return;
+                }
+                await iap.buyRemoveAds();
+              },
+      ),
+      const Divider(),
+      ListTile(
+        leading: const Icon(Icons.restore),
+        title: Text(l10n.restorePurchases),
+        onTap: () => iap.restorePurchases(),
+      ),
+    ];
+  }
 }