Fix CodeQL security alerts

[AevumDecessus]

Fix 3 CodeQL security findings from PR #45.

Changes

Medium Severity

• Add missing permissions: contents: read to validate-release workflow
• Remove exception detail from healthz endpoint to prevent information disclosure

Proactive Security

• Add CodeQL workflow to scan PRs and pushes to dev/main
• Scan Python, JavaScript, and GitHub Actions workflows
• Catches security issues before they reach main

Related

• Fixes CodeQL alerts blocking PR Release 1.0.0 #45
• Does not address the high severity sonar.yaml alert (already following documented safe pattern)

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

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