Add signing certificate fingerprint to README

[neocryptics]

Pre-submission Checklist

• I have searched existing issues to ensure this hasn't been requested before.
• This request covers a single, specific improvement.
• The issue title is concise and descriptive.

Category

🔧 Other

Is your feature request related to a problem?

Yes, this is a security concern.

Proposed Solution

Add the certificate signing fingerprint to README and/or website in order to allow people to verify all authenticity using apps like AppVerifier.

Alternatives Considered

No response

Visual Context & Attachments

No response