chore: pos variant

[ignaciosantise]

This pull request introduces support for a new "polygon" variant in the POS app, enabling dynamic theming and branding based on an environment variable. It also adds a SecondaryLogo component that conditionally displays the Polygon logo, updates the theme with new color options, and upgrades several @walletconnect dependencies to a newer canary version. The most important changes are grouped below:

Variant Support and Theming:

• Added EXPO_PUBLIC_VARIANT to .env.example to allow switching between "default" and "polygon" variants. The app now reads this variable to adjust theming and branding. [1] [2]
• Updated the Sentry initialization to include the current variant in the environment for better error tracking.
• Modified the payment success screen to use different background colors and themes depending on the selected variant. [1] [2]

Branding Components:

• Introduced a new SecondaryLogo component that displays the Polygon logo when the "polygon" variant is active, and integrated it into the home, amount, and payment success screens. [1] [2] [3] [4] [5] [6] [7]
• Added and updated styles for the new logo component in relevant screens. [1] [2]

Theme and Color Updates:

• Added new color tokens for "polygon-payment-success" and related UI elements in both light and dark themes. [1] [2] [3] [4]

Dependency Upgrades:

• Upgraded @walletconnect/core, @walletconnect/pos-client, @walletconnect/react-native-compat, and @walletconnect/sign-client to version 2.23.1-canary-init.6 for improved compatibility and features. [1] [2]
• Cleaned up and removed old or redundant @walletconnect dependency entries in package-lock.json. [1] [2] [3] [4] [5]

These changes make the app more flexible for multi-branding and improve maintainability by centralizing variant-based logic and theming.