* iam: add ECDSA support for OIDC token validation
Fixesseaweedfs/seaweedfs#8148
* iam: refactor OIDC ECDSA tests and add failure cases
- Refactored TestOIDCProviderJWTValidationECDSA to use t.Run
- Added sub-tests for expired token, wrong key, invalid issuer, and invalid audience
* Update weed/iam/oidc/oidc_provider_test.go
Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>
* iam: improve error type assertions for OIDC invalid signature tests
- Updated both RSA and ECDSA tests to specifically check for ErrProviderInvalidToken
* iam: pad EC coordinates in OIDC tests to comply with RFC 7518
- Coordinates are now zero-padded to the full field size (e.g., 32 bytes for P-256)
- Ensures interoperability with strict OIDC providers
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Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>