STA-302: Add relative-path copy control

[claudecafe]

Summary

• Add an accessible inline copy control beside each file path.
• Copy the repository-relative path with success feedback without triggering file navigation or folding.
• Keep the control visually compact and aligned across desktop and narrow layouts.
• Update Deliver instructions to publish and verify both production websites after merge.

Checks

• pnpm check

Accepted product checkpoint: 3c59135