Add API endpoints and management pages for software versions and upgrade paths

- Implemented API endpoint for managing software versions in `products_software_versions.php`.
- Created management page for software version assignments in `products_software_assignments.php`.
- Developed upgrade paths management functionality in `products_software_upgrade_paths_manage.php`.
- Enhanced software version details page in `products_software_version.php`.
- Added form handling and validation for software version creation and updates in `products_software_version_manage.php`.
- Introduced pagination and filtering for software versions in `products_software_versions.php`.
- Implemented success message handling for CRUD operations across various pages.

style/admin.css

@@ -46,7 +46,6 @@ header {
   width: 100%;
   height: 55px;
   background-color: var(--color-white);
-  box-shadow: 0px 0px 4px 1px rgba(0, 0, 0, 0.15);
 }
 
 header a {
@@ -242,7 +241,6 @@ main h2 span {
 }
 
 main .content-title {
-  border-bottom: 1px solid #dbdddf;
   display: flex;
 }
 
@@ -1006,10 +1004,6 @@ main .manage-order-table .delete-item:hover {
   padding-left: 5px;
 }
 
-.table table thead tr {
-  border-bottom: 1px solid #f0f1f2;
-}
-
 .table table tbody tr:first-child td {
   padding-top: 10px;
 }