fix: improve OwnerDashboard with input validation, loading states and UX fixes

[PranavGadge01]

Summary

Improves the OwnerDashboard component with code quality and UX fixes.

Changes

• Added input validation for IPFS hash, image hash and signature fields
• Added loading states for mint button and session signer setup button
• Auto-clear status messages after 5s and mint status after 8s
• Disabled form inputs while minting is in progress to prevent duplicate submissions
• Added clickable Etherscan link after successful mint transaction
• Fixed empty useEffect that was doing nothing
• Added proper labels to all form inputs for better accessibility
• Reset form fields after successful mint
• Wrapped setupSessionSigner with useCallback to prevent unnecessary re-renders
• Removed emojis from UI text for cleaner professional appearance
• Changed "Logout" to "Sign Out" and "Connected ✅/❌" to plain text status

Testing

• Portal loads and authenticates successfully
• Wallet connects and displays correctly
• Form validation rejects invalid input formats
• Buttons show loading state when processing
• Status messages auto-clear after timeout