docs: add logo, badges, and CodeQL security workflow

[srbouffard]

Changes

Logo

Adds assets/arok_logo.png and displays it centered above the README title (360px wide — legible but not overwhelming).

Badges

Five badges in a centered row beneath the logo:

• Release — links to latest GitHub release
• CI — live status of the ci.yml workflow on main
• CodeQL — live status of the new security scan
• Go version — static 1.26+ badge
• License — MIT

CodeQL workflow (.github/workflows/codeql.yml)

• Runs on push/PR to main and on a weekly Monday schedule
• Uses security-and-quality query suite for Go
• Findings surface as GitHub Security Advisories / code scanning alerts

[github-advanced-security]

You are seeing this message because GitHub Code Scanning has recently been set up for this repository, or this pull request contains the workflow file for the Code Scanning tool.

What Enabling Code Scanning Means:

• The 'Security' tab will display more code scanning analysis results (e.g., for the default branch).
• Depending on your configuration and choice of analysis tool, future pull requests will be annotated with code scanning analysis results.
• You will be able to see the analysis results for the pull request's branch on this overview once the scans have completed and the checks have passed.

For more information about GitHub Code Scanning, check out the documentation.