[WAL-1158] fix(openid4vci): align wallet nonce handling with 1.0

[szijpeter]

Summary

Implements WAL-1158 as the wallet-side OpenID4VCI 1.0 correction for proof nonce handling and invalid_nonce recovery.

When an issuer advertises nonce_endpoint, the wallet obtains a fresh c_nonce for each proof-bound credential request. When it does not, the wallet still creates the required proof without a nonce claim; token-response c_nonce values and access tokens are never used as proof nonces.

The matching enterprise consumer is walt-id/waltid-identity-enterprise#547.

What Changed

• adds a reusable typed KMP NonceRequestBuilder for nonce-endpoint responses with sanitized failures
• makes proof nonce input nullable and omits the JWT nonce claim when no nonce was obtained
• obtains a fresh metadata-advertised nonce for each proof-bound credential request
• removes token-response c_nonce and access-token fallback from proof construction and isolated token results
• retries a full credential request exactly once after an issuer returns the standard invalid_nonce error, using a newly fetched nonce and freshly signed proof
• keeps isolated fetch-credential calls single-shot and propagates the typed credential error so API clients explicitly control any retry
• maps the exact invalid_nonce credential error to the Wallet2 HTTP API response
• updates focused wallet, route, and nonce-client coverage plus protocol documentation

Architecture Notes

NonceRequestBuilder is deliberately a small protocol client: it requests and parses the nonce response, preserves cancellation, and redacts malformed response material. The higher-level issuance flow owns the bounded retry because it alone can fetch a nonce and regenerate a proof safely.

The wallet intentionally applies no HTTPS-enforcement or redirect-rejection policy to nonce_endpoint; transport reachability remains the HTTP client's concern. This is the agreed non-standard-compliance trade-off for these PRs.

This PR is the prerequisite for walt-id/waltid-identity#1935, which is restacked to consume the shared implementation instead of carrying WAL-1158 inside the broader WAL-995 change.

Caveats and Follow-Ups

• Automatic recovery is limited to one retry and only to the standard invalid_nonce error. Other credential errors propagate unchanged.
• Isolated API consumers receive the typed error rather than an implicit replay, because they own the surrounding issuance state.

Breaking Changes

• TokenRequestBuilder.TokenResponse.c_nonce and c_nonce_expires_in are removed.
• RequestTokenResult.cNonce is removed.
• RequestNonceResult.nonce and proof-builder nonce inputs are nullable so issuers can require proofs without advertising a Nonce Endpoint.

[linear-code]

WAL-1158

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[chsavvaidis]

see comment

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud