refactor: improve notification naming and introduce type-safe enums

- Rename billFwd* to billsNotification* for clarity
- Rename rentDueNotification* to rentNotification* for consistency
- Rename utilBillsProofOfPayment to billsProofOfPayment
- Introduce enums for type safety:
  - BillsNotificationStrategy (WhenPayed, WhenAttached)
  - BillsNotificationStatus (Scheduled, Sent, Failed)
  - RentNotificationStatus (Sent, Failed)
- Replace "pending" status with "scheduled" for better semantics
- Fix function names to proper camelCase
- Fix incorrect import path in web-app/app/lib/format.ts

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

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

web-app/app/[locale]/share/proof-of-payment/combined/[id]/route.tsx

@@ -23,12 +23,12 @@ export async function GET(request: Request, { params: { id } }: { params: { id:
     const location = await dbClient.collection<BillingLocation>("lokacije")
         .findOne({ _id: locationID }, {
             projection: {
-                utilBillsProofOfPayment: 1,
+                billsProofOfPayment: 1,
                 shareTTL: 1,
             }
         });
 
-    if (!location?.utilBillsProofOfPayment) {
+    if (!location?.billsProofOfPayment) {
         notFound();
     }
 
@@ -38,7 +38,7 @@ export async function GET(request: Request, { params: { id } }: { params: { id:
     }
 
     // Convert fileContentsBase64 from Base64 string to binary
-    const fileContentsBuffer = Buffer.from(location.utilBillsProofOfPayment.fileContentsBase64, 'base64');
+    const fileContentsBuffer = Buffer.from(location.billsProofOfPayment.fileContentsBase64, 'base64');
 
     // Convert fileContentsBuffer to format that can be sent to the client
     const fileContents = new Uint8Array(fileContentsBuffer);
@@ -47,8 +47,8 @@ export async function GET(request: Request, { params: { id } }: { params: { id:
         status: 200,
         headers: {
             'Content-Type': 'application/pdf',
-            'Content-Disposition': `attachment; filename="${location.utilBillsProofOfPayment.fileName}"`,
-            'Last-Modified': `${location.utilBillsProofOfPayment.fileLastModified}`
+            'Content-Disposition': `attachment; filename="${location.billsProofOfPayment.fileName}"`,
+            'Last-Modified': `${location.billsProofOfPayment.fileLastModified}`
         }
     });
 }