Handle empty presentation matches without crashing

[nodh]

Summary

• reject Presentation Exchange descriptors that have no matching stored credential before the selection UI is built
• guard related selection and presentation-result code paths that assumed non-empty collections
• add a regression test for the empty-match Presentation Exchange case

Verification

• ./gradlew :shared:testAndroidHostTest --tests ui.presentation.CredentialSelectionProviderTest

Fixes #436

[nodh]

iOS Build is fixed in #434

[nodh]

Closed in favor of #438

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Route empty PE matches through the no-credential state

When an OpenID4VP/DCAPI Presentation Exchange request has at least one descriptor with no local match, this check now throws during toCredentialSelectionProvider(). In the graph-based flows (DefaultPresentationGraphViewModel/DCAPIPresentationGraphViewModel), that exception is converted to UiStateError, and PresentationGraphView immediately forwards it to onError, which WalletNavigation handles by popping back to HomeScreenRoute. The result is that a normal “no matching credential” case is now surfaced as a fatal error instead of the existing no-match UX used in AuthenticationViewModel.onConsent, so users lose the explanatory screen and are bounced out of the flow.

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