feature(PayPal): collect and send device_info to determine app switch eligibility

[santugowda]

Summary of changes

Sends device information as a nested app_switch_context object in PayPal Hermes requests when enablePayPalAppSwitch is enabled. This data is used downstream to determine app switch eligibility.

JSON structure sent to BTGW:

{
  "launch_paypal_app": true,
  "app_switch_context": {
    "device_info": {
      "model": "SM-A166U",
      "memory_available_mb": 350,
      "memory_total_mb": 4096
    },
    "native_app": {
      "app_url": "https://...",
      "os_type": "ANDROID",
      "os_version": "35"
    }
  }
}

Changes:

• PayPalVaultRequest / PayPalCheckoutRequest: replaced flat os_type, os_version, merchant_app_return_url keys with nested app_switch_context.native_app object
• PayPalInternalClient: injectDeviceInfo() adds device_info (model, memory_available_mb, memory_total_mb) into app_switch_context
• PayPalRequest: updated constants for new nested key structure
• Updated unit and instrumentation tests to verify nested structure

AI Usage

Which AI Agent Was Used?

• Claude

How was AI used?
Code generation, cross-codebase analysis (Android SDK, BTGW, backend), refactoring from flat to nested JSON structure, and writing tests.

Estimated AI Code Contribution

• less than 30%
• 30 - 60%
• 60 - 100%

Checklist

• Added a changelog entry
• Tested and confirmed payment flows affected by this change are functioning as expected

Authors

• @santugowda

---

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Inner Source Checklist

• Added all labels to the PR
• Provide steps to test the flows changed, if applicable in the summary
• Demo video of the functionality, if applicable
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[jaxdesmarais]

@santugowda please follow the Inner Source Process in the PR description.

[santugowda]

/ready

[santugowda]

/inner source