feat: Implement invoice generation and emailing functionality

- Added invoice generation logic using DomPDF.
- Integrated invoice data retrieval from the API.
- Implemented language determination for invoices based on customer data.
- Added options to email invoices to customers and admin.
- Included HTML output option for direct viewing in the browser.
- Ensured proper redirection and error handling throughout the process.

api/v2/get/software_available.php

@@ -161,6 +161,7 @@ if (isset($criterias['sn']) && $criterias['sn'] != ''){
                 $debug['decision'] = 'No active software assignments found';
             }
         } else {
+            $available_upgrades = 0;
             $has_priced_options = false;
             $has_latest_version_different = false;
 
@@ -242,6 +243,8 @@ if (isset($criterias['sn']) && $criterias['sn'] != ''){
                 }
 
                 if ($show_version) {
+                    $available_upgrades++;
+                    
                     //Check if there's a valid license for this upgrade
                     if ($final_price > 0 && $sw_version_license) {
                         //Check if the license is valid
@@ -286,23 +289,18 @@ if (isset($criterias['sn']) && $criterias['sn'] != ''){
                 }
             }
 
-            // Apply the logic:
-            // 1. If there are priced options -> "yes"
-            // 2. If no priced options but current version != latest flagged version -> "yes"
-            // 3. Default -> "no"
-            if ($has_priced_options) {
+            // Simple logic: if any upgrades are available to show, return "yes"
+            if ($available_upgrades > 0) {
                 $software_available = "yes";
-                $availability_reason = "Has priced upgrade options available";
-            } elseif ($has_latest_version_different) {
-                $software_available = "yes";
-                $availability_reason = "Has free latest version available";
+                $availability_reason = "Software upgrades available";
             } else {
                 $software_available = "no";
-                $availability_reason = "No upgrades available or already on latest";
+                $availability_reason = "No upgrades available";
             }
 
             if (debug) {
                 $debug['final_decision'] = [
+                    'available_upgrades' => $available_upgrades,
                     'has_priced_options' => $has_priced_options,
                     'has_latest_version_different' => $has_latest_version_different,
                     'software_available' => $software_available,