Fix sandbox detection

[yusuftor]

Summary

• Uses AppTransaction.environment (iOS 16+) as the primary sandbox detection method in DeviceHelper.detectSandbox(), with the existing receipt URL path check as a fallback for older iOS versions.
• The previous approach only checked Bundle.main.appStoreReceiptURL for "sandboxReceipt", which could incorrectly return false for apps using Stripe or other non-StoreKit payment methods — including during App Review.
• Leverages the AppTransaction.shared call already made in ReceiptManager.setAppTransactionId() to also capture the environment, avoiding any additional async work.

Checklist

• I added/updated tests or detailed why my change isn't tested.
• I added an entry to the CHANGELOG.md for any breaking changes, enhancements, or bug fixes.
• All unit tests pass.
• All UI tests pass.
• Demo project builds and runs on iOS.
• Demo project builds and runs on Mac Catalyst.
• Demo project builds and runs on visionOS.
• I have run swiftlint in the main directory and fixed any issues.
• I have updated the SDK documentation as well as the online docs.
• I have reviewed the contributing guide

🤖 Generated with Claude Code

Greptile Summary

This PR fixes incorrect sandbox detection for apps using Stripe or other non-StoreKit payment methods. The previous approach only checked the receipt URL path for "sandboxReceipt", which would return false for apps without StoreKit receipts - even during App Review or TestFlight.

The fix leverages AppTransaction.environment (available on iOS 16+) as the primary detection method, with the receipt URL check as a fallback for older iOS versions or when AppTransaction data isn't available yet. This is captured in a new static property ReceiptManager.isSandboxEnvironment that's set during initialization.

Key changes:

• Added ReceiptManager.isSandboxEnvironment static property set from AppTransaction.shared
• Updated DeviceHelper.detectSandbox() to check this property before falling back to receipt URL
• Proper fallback ensures backward compatibility and handles initialization timing
• Added basic tests and CHANGELOG entry

The implementation is clean and follows the existing pattern used by appTransactionId and appId static properties.

Confidence Score: 5/5

• This PR is safe to merge with no risk - it's a well-designed fix with proper fallback behavior
• The implementation correctly uses AppTransaction.environment (iOS 16+) as the primary sandbox detection method while maintaining backward compatibility with the receipt URL fallback. The logic is sound, follows existing patterns in the codebase, and includes appropriate tests and documentation.
• No files require special attention

Important Files Changed

Filename	Overview
CHANGELOG.md	Added version 4.14.1 entry documenting the sandbox detection fix - clear and accurate description of the change
Sources/SuperwallKit/Network/Device Helper/DeviceHelper.swift	Added check for AppTransaction-based sandbox detection before falling back to receipt URL method - logic is sound with appropriate fallback behavior
Sources/SuperwallKit/StoreKit/Products/Receipt Manager/Receipt Manager/ReceiptManager.swift	Added static property to capture sandbox environment from AppTransaction - follows existing pattern for appTransactionId and appId
Tests/SuperwallKitTests/StoreKit/Products/Receipt Manager/ReceiptManagerTests.swift	Added basic tests for the new isSandboxEnvironment property - verifies property can be set and read correctly

_{Last reviewed commit: 77138ea}