feat(paywall): offer xBull, LOBSTR, Albedo and Rabet, and make the list configurable

[pedro-pelicioni]

feat(paywall): offer xBull, LOBSTR, Albedo and Rabet, and make the list configurable

Branch: fix/74-wallet-coverage
Screenshots: harness/shots/before-wallet-modal.png → harness/shots/after-wallet-modal.png

The gap

useSWKConnection initialises Stellar Wallets Kit with four modules:

modules: [new FreighterModule(), new HanaModule(), new KleverModule(), new OneKeyModule()]

Anyone holding USDC in xBull, LOBSTR, Albedo or Rabet cannot pay, and the modal
gives no hint that their wallet was never an option. SWK ships a zero-config
module for each of them (@creit.tech/stellar-wallets-kit/modules/{xbull,lobstr,albedo,rabet}).

Opening the real modal against each version confirms the difference:

	wallets offered
before	Freighter, Hana, Klever, OneKey — 4
after	xBull, Albedo, Freighter, LOBSTR, Rabet, Hana, Klever, OneKey — 8

The change

• Offer all eight, Freighter first.
• Let the host narrow and order the list: stellarWallets on PaywallConfig
  flows through to window.x402.config.wallets, the same path stellarRpcUrl
  already takes. Omitting it keeps every wallet.
• Unknown ids are dropped with a console warning, and a list with no usable id
  falls back to all wallets, so a config typo degrades instead of leaving a
  paywall nobody can pay.

Structure

The id list and the resolution logic live in walletIds.ts with no SWK
import. The SWK modules are browser-only — importing one under Node throws on
@stellar/freighter-api's ESM interop — so keeping them apart is what makes
the selection logic unit-testable at all. walletModules.ts maps ids to modules
through a Record<WalletId, ...>, so adding an id without wiring up its module
is a build error rather than a crash inside the modal.

Ledger, Trezor and WalletConnect are deliberately excluded: their modules need
per-integrator configuration (a transport, a project id) and cannot be enabled
by id alone.

Cost

~99 KB uncompressed for the four added wallets (3,749,116 → 3,850,869 bytes).
If that is too much for the default, the same mechanism supports shipping four
by default and letting hosts opt into the rest — say the word and I will flip it.

Tests

9 new cases covering the default list, explicit ordering, case/whitespace
tolerance, de-duplication, unknown-id warning, and the all-unknown fallback.

---

Part of #74.

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