feat(ssh-remote): improve connection dialog search and SSH config parsing

[bobleer]

Summary

• Add search inputs for saved SSH connections and SSH config hosts in the connection dialog, with deduplicated config host filtering preserved.
• Polish saved-list layout: section headers, scrollable list with hidden scrollbar, and simplified item styling.
• Fix manual SSH config fallback parsing to correctly handle double-quoted directive values (e.g. IdentityFile "~/.ssh/my key").

Test plan

• pnpm run type-check:web
• cargo check -p bitfun-services-integrations
• Open SSH connection dialog with multiple saved connections and verify search filters by name/host/username
• Verify SSH config hosts section hides entries already saved and supports search
• Verify manual SSH config fallback parses quoted IdentityFile, HostName, User, and Port values correctly