Feature request: Display JWT Header when decoding

**Is your feature request related to a problem? Please describe.**
When decoding JWTs only the payload is displayed. To view the header and the signature I have to use other tools.

**Describe the solution you'd like**
It would be great to see both the header and signatures block decoded in the CyberChef interface, or at least the header.

**Describe alternatives you've considered**
N/A

**Additional context**
N/A

Start by locating the JWT decoding operation and the CyberChef interface that displays its current payload output. Trace how the decoded result is presented, then define completion as showing the JWT header and, if supported by the chosen scope, the signature block alongside the payload.

Written by the indexing model from the issue text.