feat(review): request a store review after a 3-star win, once

Adds an in-app review prompt gated by ReviewPromptPolicy: only after a
3-star stage win, once the player has cleared >=5 stages, at most once
ever (persisted reviewRequested flag). ReviewService swallows all
failures and only burns the one-shot when the store actually shows the
sheet, so an unavailable store retries on a later win. StoreReviewer
wraps in_app_review behind a Reviewer seam so unit tests skip platform
channels. 13 new tests; full suite 194 green.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

pubspec.lock

@@ -413,6 +413,22 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "0.4.8+1"
+  in_app_review:
+    dependency: "direct main"
+    description:
+      name: in_app_review
+      sha256: "364db0c160b37fe7fad9cdaa18f968473924b17368869010af902760421b6bf8"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.0.12"
+  in_app_review_platform_interface:
+    dependency: transitive
+    description:
+      name: in_app_review_platform_interface
+      sha256: fed2c755f2125caa9ae10495a3c163aa7fab5af3585a9c62ef4a6920c5b45f10
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.0.5"
   intl:
     dependency: transitive
     description:
@@ -842,6 +858,70 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.4.0"
+  url_launcher:
+    dependency: transitive
+    description:
+      name: url_launcher
+      sha256: f6a7e5c4835bb4e3026a04793a4199ca2d14c739ec378fdfe23fc8075d0439f8
+      url: "https://pub.dev"
+    source: hosted
+    version: "6.3.2"
+  url_launcher_android:
+    dependency: transitive
+    description:
+      name: url_launcher_android
+      sha256: "3bb000251e55d4a209aa0e2e563309dc9bb2befea2295fd0cec1f51760aac572"
+      url: "https://pub.dev"
+    source: hosted
+    version: "6.3.29"
+  url_launcher_ios:
+    dependency: transitive
+    description:
+      name: url_launcher_ios
+      sha256: cfde38aa257dae62ffe79c87fab20165dfdf6988c1d31b58ebf59b9106062aad
+      url: "https://pub.dev"
+    source: hosted
+    version: "6.3.6"
+  url_launcher_linux:
+    dependency: transitive
+    description:
+      name: url_launcher_linux
+      sha256: d5e14138b3bc193a0f63c10a53c94b91d399df0512b1f29b94a043db7482384a
+      url: "https://pub.dev"
+    source: hosted
+    version: "3.2.2"
+  url_launcher_macos:
+    dependency: transitive
+    description:
+      name: url_launcher_macos
+      sha256: "368adf46f71ad3c21b8f06614adb38346f193f3a59ba8fe9a2fd74133070ba18"
+      url: "https://pub.dev"
+    source: hosted
+    version: "3.2.5"
+  url_launcher_platform_interface:
+    dependency: transitive
+    description:
+      name: url_launcher_platform_interface
+      sha256: "552f8a1e663569be95a8190206a38187b531910283c3e982193e4f2733f01029"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.3.2"
+  url_launcher_web:
+    dependency: transitive
+    description:
+      name: url_launcher_web
+      sha256: "4bd2b7b4dc4d4d0b94e5babfffbca8eac1a126c7f3d6ecbc1a11013faa3abba2"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.4.1"
+  url_launcher_windows:
+    dependency: transitive
+    description:
+      name: url_launcher_windows
+      sha256: "712c70ab1b99744ff066053cbe3e80c73332b38d46e5e945c98689b2e66fc15f"
+      url: "https://pub.dev"
+    source: hosted
+    version: "3.1.5"
   uuid:
     dependency: transitive
     description: