Aligns the Unity SDK's custom variables API with React Native and Flutter
SDKs by using a CustomVariableValue type with factory method pattern
instead of raw Dictionary<string, string>.

This allows adding new variable types (e.g., numbers, booleans) in the
future without breaking changes.

Usage:
```csharp
var options = new PaywallOptions(
    customVariables: new Dictionary<string, CustomVariableValue>
    {
        { "player_name", CustomVariableValue.String("John") },
        { "level", CustomVariableValue.String("42") },
    }
);
```

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

…eValue

- Use PaywallActivityLaunchOptions.Builder and PaywallActivityLaunchIfNeededOptions.Builder
- Convert Map<String, String> to Map<String, CustomVariableValue.String>
- Fix method signatures to match SDK API

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

- Fix incorrect Android API usage: use setOfferingIdentifier() instead of
  non-existent setOfferingId() and setPresentedOfferingContext() methods
- Update purchases-hybrid-common from 17.37.0 to 17.39.0

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

The builder's setOfferingIdentifier method requires @OptIn(InternalRevenueCatAPI)
which cannot be properly used from Java code. Use the deprecated public launch()
overloads instead for launchPaywall, which handle the internal API opt-in
themselves.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Unity requires .meta files alongside every asset. These were missing for:
- RevenueCatUI/Scripts/CustomVariableValue.cs
- IntegrationTests/Assets/APITests/PaywallOptionsAPITests.cs
- Subtester/Assets/Scripts/CustomVariablesEditor.cs

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

- Fix RevenueCat.SimpleJSON namespace reference in PaywallOptions.cs
- Add missing .meta file for PaywallsBehaviourAPITests.cs

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

The deprecated launcher.launch() overloads no longer exist in PHC 17.41.1.
Use PaywallActivityLaunchOptions.Builder pattern consistent with
launchPaywallIfNeeded.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

This belongs in the other/integration-tests2 branch (PR #735), not here.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

…ank lines

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

- Move customVariables param after purchaseLogic in PaywallOptions constructors
  to preserve positional argument compatibility with existing callers
- Skip null values in ToStringDictionary to prevent NRE when users pass
  null CustomVariableValue entries in the dictionary
- Add custom variables Inspector support to PaywallsBehaviour with
  serializable CustomVariableEntry array
- Restore PaywallsBehaviourAPITests.cs that was accidentally deleted
- Add positional argument compatibility tests to PaywallOptionsAPITests

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

… name

Also refactor PaywallOptions constructors to use constructor chaining and
eliminate redundant intermediate dictionary in CustomVariablesToJsonString.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

- Add defaultOfferingIdentifier and defaultCustomVariables fields to TesterApp
- Pre-populate PaywallScreen fields from editor values
- Add offering ID text field to Paywalls screen UI
- Replace StoreKit config with PaywallsTester products
- Set API keys and default offering in scene

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

…n.unity

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

…ariables

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>