fix: improve SSH key handling and public key modal UX

[michelroegl-brunner]

Summary

This PR fixes several SSH key handling issues and improves the public key modal user experience.

Changes Made

🔧 SSH Key Import Fixes

• Auto-trim whitespace: SSH keys now automatically have trailing whitespace and empty lines removed when pasted or uploaded
• Prevents import failures: No more manual editing required to remove extra whitespace

🔧 Public Key Modal Improvements

• Reduced textarea size: Public key textarea reduced from 120px to 60px min-height for better space usage
• Quick command section: Added pre-filled echo command for adding keys to authorized_keys
• One-click copy: Users can copy either just the key or the complete command
• Better UX: Clear separation between key display and command sections

🔧 ServerForm Enhancements

• View Public Key button: Added button in ServerForm for generated key pairs (works before saving server)
• Immediate access: Users can view public keys right after generation

Technical Details

• Modified to auto-trim whitespace in both paste and file upload handlers
• Enhanced with smaller textarea and quick command functionality
• Updated to include View Public Key button for generated keys
• All changes maintain existing functionality while improving user experience

Testing

• ✅ Build successful with no errors
• ✅ All linting checks pass
• ✅ No breaking changes to existing functionality

User Benefits

• Faster SSH key setup with fewer manual steps
• Reduced errors from whitespace issues
• Better modal layout and usability
• One-click access to public keys and commands