Add ability to share scan result via shareable link

[NaitikVerma6776]

Summary

• Adds a Share Result button on safe/danger result cards that copies a ?url= deep link to the clipboard
• Opening a shared link auto-fills the URL input and triggers a scan
• Skips the intro loader for shared links so recipients see results immediately

Closes #180

Test plan

• Scan a URL (safe or danger) and confirm Share Result appears on the result card
• Click Share Result and verify the clipboard contains origin/path?url=...
• Confirm button shows Link copied! for ~2 seconds
• Open the shared link in a new tab and confirm the input fills and scan runs automatically
• Confirm Share Result does not appear on loading or error states

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