ci(security): add Go to CodeQL language matrix

[katriendg]

Summary

Add 'go' to the CodeQL language matrix in .github/workflows/codeql-analysis.yml.

# Before
language: [ 'javascript', 'python' ]

# After
language: [ 'go', 'javascript', 'python' ]

Priority: P2 — defer until Go code exceeds ~500 lines. CodeQL static analysis only adds value once there is Go source code with meaningful call graphs to scan.

Depends on: #290 implementation PR with Terratest code must be merged first. Do not implement this issue until Go source code exists in the repository.

Acceptance Criteria

• CodeQL runs Go analysis alongside JavaScript and Python
• No false-positive security findings on initial Go codebase