add option to create location in all subsequent months

- Added toggle in LocationEditForm for adding locations to future months (disabled by default)
- Modified updateOrAddLocation action to support batch creation across subsequent months
- Only creates locations in months where no location with same name exists
- Added translations for toggle text in Croatian and English
- Fixed unused variable warning in deleteLocationById
- Improved auth.ts development comments for clarity

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

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

app/ui/LocationEditForm.tsx

@@ -60,6 +60,16 @@ export const LocationEditForm:FC<LocationEditFormProps> = ({ location, yearMonth
                         ))}
                     </div>
 
+                    {/* Show toggle only when adding a new location (not editing) */}
+                    {!location && (
+                        <div className="form-control">
+                            <label className="label cursor-pointer">
+                                <span className="label-text">{t("add-to-subsequent-months")}</span> 
+                                <input type="checkbox" name="addToSubsequentMonths" className="toggle toggle-primary" />
+                            </label>
+                        </div>
+                    )}
+
                     <div id="status-error" aria-live="polite" aria-atomic="true">
                         {
                             state.message &&