Initialize vct-registry with Express server, SD JWT VC type metadata, assets, and devepment Docker integration

[gkatrakazas]

This PR introduces the first complete version of vct-registry, providing a minimal server, initial metadata, and a simple interface for browsing type metadata information.

Added SD-JWT VC Type Metadata

Includes the first set of Type metadata entries:

• PID
• EHIC
• POR
• Diploma
• PDA1

All metadata is centrally registered and available through the public API.

Public API Endpoints

The registry exposes lightweight endpoints to:

• List all available VCTs: /api/vct
• Retrieve metadata for a specific VCT: GET /type-metadata?vct=…
• Retrieve all metadata entries: /type-metadata/all

These endpoints allow clients, issuers, and tools to easily access type information.

Static HTML UI

A simple static interface is provided, showing:

• An overview of available VCTs
• How to fetch metadata
• Basic information about the registry service

The UI is served directly from the Express server.

Server, Scripts & Integration

• Express server configured with CORS and basic health/info endpoints
• Image assets served with optimal cache rules
• Dockerfile added and service integrated into the main docker-compose setup