feat: implement language-based email template selection

Update email worker to select templates based on BillingLocation.tenantEmailLanguage:
- Change default language from 'en' to 'hr' in emailTemplates.ts
- Pass language parameter (location.tenantEmailLanguage || 'hr') to all loadAndRender calls
- Applies to email validation, rent due, and utility bills notifications

Email templates are now automatically selected based on tenant's language preference,
defaulting to Croatian when not specified.

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

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

email-worker/src/lib/emailSenders.ts

@@ -59,7 +59,7 @@ export async function sendVerificationRequests(db: Db, budget: number): Promise<
             'ownerName': ownerName,
             'location.name': location.name,
             'shareId': shareId
-        });
+        }, location.tenantEmailLanguage || 'hr');
 
         const success = await sendEmail({
             to: location.tenantEmail,
@@ -161,7 +161,7 @@ export async function sendRentDueNotifications(db: Db, budget: number): Promise<
             'currency': currency,
             'ownerName': ownerName,
             'shareId': shareId
-        });
+        }, location.tenantEmailLanguage || 'hr');
 
         const success = await sendEmail({
             to: location.tenantEmail,
@@ -254,7 +254,7 @@ export async function sendUtilityBillsNotifications(db: Db, budget: number): Pro
             'currency': currency,
             'ownerName': ownerName,
             'shareId': shareId
-        });
+        }, location.tenantEmailLanguage || 'hr');
 
         const success = await sendEmail({
             to: location.tenantEmail,

email-worker/src/lib/emailTemplates.ts

@@ -20,7 +20,7 @@ export type TemplateVariables = {
  * @param language Language code (default: 'en')
  * @returns Template content as string
  */
-export function loadTemplate(templateName: string, language: string = 'en'): string {
+export function loadTemplate(templateName: string, language: string = 'hr'): string {
     const cacheKey = `${templateName}--${language}`;
 
     // Check cache first
@@ -80,7 +80,7 @@ export function renderTemplate(template: string, variables: TemplateVariables):
 export function loadAndRender(
     templateName: string,
     variables: TemplateVariables,
-    language: string = 'en'
+    language: string = 'hr'
 ): string {
     const template = loadTemplate(templateName, language);
     return renderTemplate(template, variables);