chore: upgrade go-jose to v4 and update JWT serialization methods

[chimanjain]

chore: upgrade go-jose from v3 to v4 and update JWT serialization methods

[crozzy]

This is a change that will take more effort on account of v4 enforcing a minimum key length. That means that if anyone has short keys configured in their environments in the wild auth will potentially fail:

{"level":"ERROR","source":"main.main.func3","time":"2026-05-18T10:05:15.476020329-07:00","msg":"error exit","reason":"go-jose/go-jose: invalid key size for algorithm"}

Potential additions:

• Release notes and commit message should mention this
• config/auth.go.validate should probably check key length
• Edit local-dev/clair/config.yaml

[chimanjain]

This is a change that will take more effort on account of v4 enforcing a minimum key length. That means that if anyone has short keys configured in their environments in the wild auth will potentially fail:

{"level":"ERROR","source":"main.main.func3","time":"2026-05-18T10:05:15.476020329-07:00","msg":"error exit","reason":"go-jose/go-jose: invalid key size for algorithm"}

Potential additions:

• Release notes and commit message should mention this
• config/auth.go.validate should probably check key length
• Edit local-dev/clair/config.yaml

Thanks @crozzy . I'll add additional checks and update UT's. Please review once I commit them

[chimanjain]

@crozzy can you please re review