Add repository links to closing slides

[justinyoo]

Summary

Add the GitHub repository URL to the closing slide in the English, Korean, and UbuCon decks. Move each closing link group upward so it remains visually centered between the session title and speaker details after adding the second line.

Change type

• Presentation content
• Presentation design
• PowerShell
• Bash
• Bicep
• Documentation or repository maintenance

Validation

• Marp HTML generation succeeds.
• Updated slides were visually reviewed.
• PowerShell files parse without errors.
• Bash files pass bash -n.
• Bicep files build successfully.
• No generated files, credentials, or sensitive data are included.

Additional checks:

• Verified the repository link renders exactly once in each deck.
• Verified title-to-links and links-to-speaker center spacing differs by no more than 3 px in each deck.

Screenshots

Not included.

Related issues

None.