Add GitHub Actions CI workflow

[VisionaireLabs]

Task

Add a .github/workflows/ci.yml workflow that runs on every PR and push to main.

Requirements

• Validate all .mjs scripts parse without errors (node --check)
• Validate all .sh scripts with bash -n
• Check that required files exist: SOUL.md, AGENTS.md, USER.md, MEMORY.md, HEARTBEAT.md
• Run on: ubuntu-latest, Node 20

Acceptance Criteria

• .github/workflows/ci.yml created
• Workflow triggers on push to main and pull_request
• All checks pass on current repo state
• README badge added pointing to workflow status