fix: update OAuth Authorization Server Metadata endpoint construction

[nanderstabel]

Description of change

This change corrects the logic in the get_authorization_server_metadata function to properly construct the metadata URL as specified in RFC 8414.

Previously, the well-known path was appended to the issuer's path. The logic is now fixed to place the issuer's path components after the /.well-known/oauth-authorization-server segment.

Example:

Before: https://example.com/issuer -> https://example.com/issuer/.well-known/oauth-authorization-server
After: https://example.com/issuer -> https://example.com/.well-known/oauth-authorization-server/issuer

Furthermore, in line with RFC 8414 Section 5, a fallback to the /.well-known/openid-configuration endpoint is added that will be used when the /.well-known/oauth-authorization-server does not exist.

Finally, the amount of retries is reduced from 5 to 2 in order to reduce some significant unnecessary user-facing delay (this decreases max duration from 31 secs to 3 secs).

Links to any relevant issues

https://openid.net/specs/openid-4-verifiable-credential-issuance-1_0-15.html#section-11.2.3-2.2
https://www.rfc-editor.org/rfc/rfc8414.html#section-3
https://www.rfc-editor.org/rfc/rfc8414.html#section-5

How the change has been tested

Existing test has been updated

Definition of Done checklist

Add an x to the boxes that are relevant to your changes.

• I have followed the contribution guidelines for this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[Copilot]

Pull Request Overview

This PR fixes the OAuth Authorization Server URL construction to comply with RFC8414 and updates proof signing algorithm handling to use strings instead of Algorithm enum types.

• Corrects the OAuth Authorization Server Metadata endpoint URL construction according to RFC8414 specification
• Changes proof signing algorithm values from enum types to strings for better API compatibility
• Updates related test code to use string-based algorithm identifiers

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
oid4vci/src/wallet/mod.rs	Implements RFC8414-compliant URL construction and updates algorithm handling logic
oid4vci/src/proof.rs	Changes KeyProofMetadata to use Vec for algorithm values
oid4vci/src/credential_issuer/credential_issuer_metadata.rs	Updates test to use string algorithm identifiers
oid4vci/src/credential_issuer/credential_configurations_supported.rs	Updates tests to use string algorithm identifiers and removes unused import

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[codecov-commenter]

Codecov Report

❌ Patch coverage is 97.82609% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
oid4vci/src/wallet/mod.rs	97.82%	1 Missing ⚠️

Files with missing lines	Coverage Δ
oid4vci/src/wallet/mod.rs	95.71% <97.82%> (+0.19%)	⬆️

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[Copilot]

Pull Request Overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated 2 comments.

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