refactor: rename share URL path from location to bills-due

- Renamed directory: app/[locale]/share/location -> app/[locale]/share/bills-due
- Updated all URL references in web-app (billActions, locationActions, ViewBillCard)
- Updated all URL references in email-worker templates (4 email templates)
- Updated documentation in sprints/email-worker.md

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

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

web-app/app/lib/actions/billActions.ts

@@ -627,7 +627,7 @@ export const uploadProofOfPayment = async (
     await cleanupExpiredShares(dbClient);
 
     // 8. REVALIDATE CACHE
-    revalidatePath(`/share/location/${shareId}`, 'page');
+    revalidatePath(`/share/bills-due/${shareId}`, 'page');
 
     return { success: true };