feat: SSH UI

[fabiovincenzi]

This PR adds SSH key management UI to git-proxy. Based on finos#987

Features

Frontend

• SSH key management section in User profile page
  • Add SSH keys via modal dialog with validation
  • Display keys by SHA-256 fingerprint with name and date
  • Delete keys by fingerprint
• HTTPS/SSH tabs in clone popup for repository URLs

Backend

Three API endpoints handle SSH key management:

• GET /api/v1/user/:username/ssh-key-fingerprints → Returns fingerprint metadata (name, fingerprint, addedAt) for the user
• POST /api/v1/user/:username/ssh-keys → Accepts public key and name, calculates fingerprint server-side
• DELETE /api/v1/user/:username/ssh-keys/:fingerprint → Removes key identified by fingerprint in URL path

Database

• Implemented SSH key CRUD operations for both File and MongoDB
• Added PublicKeyRecord type

CLI

• Updated ssh-key command to use fingerprint-based deletion