feat: Flexion channel build fixes

- Add google-services.json per-channel copy in SwitchChannel (Flexion has extra client)
- Add GooglePlay default google-services.json for fallback
- Switch Bundle Identifier per channel (Flexion → com.arkgame.ft.flexion)
- Fix FlexionSDKHelper missing BillingService import
- Fix Flexion AndroidManifest: add fullBackupContent override with flexion_backup_rules
- Add MainProcessName tools:replace to resolve gasdk/tuyoosdk manifest conflict
- Add billing:6.0.1 dependency for tuyoosdk AAR init compatibility

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

ExtraPluginCfgs/Android/googleplay/Files/google-services.json

@@ -0,0 +1,47 @@
+{
+  "project_info": {
+    "project_number": "481260393117",
+    "project_id": "fishing-travel",
+    "storage_bucket": "fishing-travel.appspot.com"
+  },
+  "client": [
+    {
+      "client_info": {
+        "mobilesdk_app_id": "1:481260393117:android:4e8da50d0ee3b5c207fa74",
+        "android_client_info": {
+          "package_name": "com.arkgame.ft"
+        }
+      },
+      "oauth_client": [
+        {
+          "client_id": "481260393117-jhq50gh6n2p6pat1bjhcgj3th1ke19jg.apps.googleusercontent.com",
+          "client_type": 1,
+          "android_info": {
+            "package_name": "com.arkgame.ft",
+            "certificate_hash": "c9cf2f5eaba383cbdd5b968d0342c49afabc32a2"
+          }
+        },
+        {
+          "client_id": "481260393117-0ah0ekk7lu5r44ko2uqlfoebgak8dmhj.apps.googleusercontent.com",
+          "client_type": 3
+        }
+      ],
+      "api_key": [
+        {
+          "current_key": "AIzaSyBU6gAwu0O28jg7-TRd_Vx2YMCH_Baa8Bw"
+        }
+      ],
+      "services": {
+        "appinvite_service": {
+          "other_platform_oauth_client": [
+            {
+              "client_id": "481260393117-0ah0ekk7lu5r44ko2uqlfoebgak8dmhj.apps.googleusercontent.com",
+              "client_type": 3
+            }
+          ]
+        }
+      }
+    }
+  ],
+  "configuration_version": "1"
+}