Remove lastName field from UserSettings and database

- Removed lastName from UserSettings interface
- Updated UserSettingsForm to remove lastName input field
- Removed lastName from all database operations
- Updated form validation schema to remove lastName validation
- Updated ViewLocationCard to use only firstName for recipient name
- Removed lastName from user settings form state tracking
- Updated Croatian translations to reflect changes

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

app/lib/db-types.ts

@@ -20,8 +20,6 @@ export interface UserSettings {
     userId: string;
     /** first name */
     firstName?: string | null;
-    /** last name */
-    lastName?: string | null;
     /** street */
     street?: string | null;
     /** town */