Summary

Add card scheme selection support to Dynamic Checkout and fix inverted restriction
logic for IIN/scheme allowlists.

Changes

Scheme selection support (card.ts)

• Pass enableCardSchemeSelection and preferredSchemes options to the card form
  from the payment method config
• Only render the single scheme logo when scheme selection is disabled (the card form
  handles scheme UI when enabled)
• Only update the scheme logo dynamically on input when scheme selection is disabled
• Add scheme_selection_enabled and scheme_selection_default_order to the Card
  type

Fix card restriction logic (card.ts)

• Fix validateCardRestrictions: restrict_to_schemes is an allowlist, but the
  previous logic treated matches as blocked — inverted the condition so cards are
  restricted only when their scheme is not in the list
• Fix handleIinRestrictionFromMessage: same inversion fix for restrict_to_iins —
  cards are now restricted only when the IIN is not in the allowlist

Impact

• Cards with schemes/IINs matching restrict_to_schemes/restrict_to_iins were
  previously incorrectly blocked. This fix unblocks valid cards and correctly blocks
  cards outside the allowlist.
• Merchants using scheme selection will now see the native card form scheme picker
  instead of a static logo.

Testing Plan

• Enable scheme selection on a payment method config (scheme_selection_enabled: true)
• Enter a co-branded card number (e.g. Mastercard/Maestro BIN) and verify the scheme
  selector appears
• Verify the single scheme logo does not render when scheme selection is enabled
• Configure restrict_to_schemes: ["mastercard"], enter a Mastercard-eligible card,
  and verify it is allowed
• With the same config, select a scheme not in the allowlist and verify the card is
  restricted
• Configure restrict_to_iins with a specific IIN, enter a card matching that IIN,
  and verify it is allowed
• Enter a card with a different IIN and verify it is restricted
• Disable scheme selection and verify the dynamic logo still updates on input

Additional Context

The restriction logic used variable names like isBlockedScheme / blockedScheme
which led to treating the allowlist as a blocklist. The fix renames and simplifies
the logic to make intent clear (hasAllowedScheme, isAllowedIin).