Discoverability: add GitHub repository topics #25

Problem

OpenDevIndex currently has no GitHub repository topics even though the project already has a clear technology-index / knowledge-map identity. This weakens GitHub discovery and makes the repository harder to surface for relevant searches.

Recommended topics

Use a focused set that describes the actual project rather than future scale claims:

• technology
• knowledge-base
• knowledge-graph
• developer-tools
• software-engineering
• computer-science
• programming
• open-source
• artificial-intelligence
• cybersecurity
• devops
• learning-resources

Acceptance criteria

• Add focused GitHub topics to the repository About metadata
• Keep topics aligned with actual published coverage
• Avoid branch-count / record / popularity claims
• Revisit the set as Technology Universe coverage becomes broader

This is repository metadata only; it does not change the knowledge-module model or quality bar.