Add configuration for warranty and payment options, update email templates, and implement marketing file migration

- Created STEP3.txt for business rules and payment configurations.
- Modified listPartner function parameter order in functions.php.
- Updated invoice email template to reflect new contact details.
- Revised PDF invoice template to include updated contact information.
- Added user session checks in index.php for improved security.
- Introduced marketing_migrate.php to migrate existing marketing files to the database.
- Increased max-height of content blocks in admin.css for better UI.

style/admin.css

@@ -591,7 +591,7 @@ main .content-block-wrapper .content-block {
   width: 100%;
   margin: 0 10px;
   border-radius: 3px;
-  max-height: 300px;
+  max-height: 400px;
   overflow-y: auto;
 }