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>

pubspec.yaml

@@ -16,7 +16,7 @@ publish_to: 'none' # Remove this line if you wish to publish to pub.dev
 # https://developer.apple.com/library/archive/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html
 # In Windows, build-name is used as the major, minor, and patch parts
 # of the product and file versions while build-number is used as the build suffix.
-version: 1.0.0+1
+version: 1.0.0+2
 
 environment:
   sdk: ^3.9.2