[FEATURE] Add copy button for repository URL

[ascender1729]

Description

Add a copy-to-clipboard button next to the repository URL input field for easy sharing.

Why Needed

• Users often want to share the current repo they're viewing
• One-click copying improves UX
• Common pattern in developer tools

Implementation Details

• Add clipboard icon button next to URL input
• Use Clipboard API (navigator.clipboard.writeText)
• Show visual feedback on successful copy
• Fallback for older browsers

Files to Modify

• src/components/results/ResultsContainer.svelte

Code Example

<button 
  onclick={() => navigator.clipboard.writeText(repoUrl)}
  title="Copy URL"
  aria-label="Copy repository URL"
>
  <ClipboardIcon />
</button>

Acceptance Criteria

• Copy button appears next to repo URL
• Clicking copies URL to clipboard
• Visual feedback shown (icon change or tooltip)
• Accessible with keyboard

Time Estimates

• With AI: 50 minutes
• Without AI: 350 minutes