Add Copy-to-Clipboard Feedback

[97115104]

Labels: good first issue, enhancement, frontend

Description

When users click copy buttons, there's minimal feedback. Add visual confirmation when content is copied.

Tasks

• Add "Copied!" tooltip or text change on copy
• Add success animation (color change, checkmark)
• Reset button after 2 seconds
• Handle copy failures gracefully

Files to modify

• /static/attestation-tool.js
• /static/style.css

Expected outcome

Clear visual feedback when users copy attestation URLs or codes.