[WALLET-185] Add login_hint and scope parameters to signedDcApiRequest

[frostevent]

Summary

Extends signedDcApiRequest (server DC API signed request) with optional loginHint and scope, and unifies its parameter type with authorizationUrl.

• DCAPIAuthorizationRequestParams is now ServerAuthorizationRequestParams & { expectedOrigins } — the same type authorizationUrl accepts, plus the required non-empty expectedOrigins. This brings in:
  • scope (optional) and dcqlQuery as a mutually-exclusive union — exactly one is required, matching authorizationUrl semantics; dcql_query is now optional in the payload.
  • loginHint (optional) → emitted as login_hint.
  • state (optional) → emitted as state, keeping the DC API payload consistent with the redirect flow.
• Deduplicated the scope XOR dcqlQuery validation into assertScopeOrDcql in internal.ts, now shared by buildAuthorizationSearchParams and the DC API path (runtime guard for JS callers; the union type already guards TS callers).

Tests

• Extended the main DC API test with state / loginHint assertions.
• Added a scope-based request test and a both-scope-and-dcqlQuery rejection test.
• Full suite passes (19 server + 6 common); yarn check-all (format, lint, build, publint) is green; common verified runtime-pure.

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