feat: support DDC (Device Data Collection) next action in payment flow

[AbhishekChorotiya]

Description

The SDK needs to handle a new invoke_ddc next action type returned by the backend during payment confirmation. Device Data Collection (DDC) is required by certain connectors to perform device fingerprinting before redirecting the user for authentication (e.g., 3DS).

Requirements

• When next_action.type is invoke_ddc, the SDK should:
  1. Read ddc_data (iframe_url, timeout_ms) from the payment confirmation response
  2. Inject a hidden iframe pointing to the DDC URL
  3. Listen for a postMessage from the iframe containing the next redirect action
  4. Redirect the user to the URL received, respecting redirect_mode
  5. Fail gracefully on timeout or missing data with proper cleanup

Acceptance Criteria

• New invoke_ddc next action type is handled in intentCall
• Hidden iframe is created and cleaned up properly (no DOM leaks)
• Timeout mechanism prevents indefinite waiting
• Redirect respects redirect_mode (required vs if_required)
• Error handling covers missing iframe_url, timeout, and malformed messages