Rename firstName to ownerName with updated validation

- Renamed firstName to ownerName in UserSettings interface
- Updated UserSettingsForm field to accept full name (first and last)
- Set maximum length to 25 characters for owner name field
- Updated all database operations to use ownerName
- Changed English label from "First Name" to "Your First and Last Name"
- Updated Croatian translations to match (Vaše ime i prezime)
- Updated form validation schema and error messages
- Removed old lastName-related translations
- Updated ViewLocationCard to use ownerName for recipient

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

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

app/lib/db-types.ts

@@ -18,8 +18,8 @@ export interface YearMonth {
 export interface UserSettings {
     /** user's ID */
     userId: string;
-    /** first name */
-    firstName?: string | null;
+    /** owner name */
+    ownerName?: string | null;
     /** street */
     street?: string | null;
     /** town */