Reorder docs to prioritize transactional/bulk sending over sandbox

Move sending, domains, templates, stats, and email logs sections
before sandbox testing in both README and test plan to reflect
that production email sending is the primary use case.

Author: SergeyKorolev

README.md

@@ -124,19 +124,19 @@ mailtrap domains list --output text
 | Group | Commands |
 |-------|----------|
 | **Sending** | `send transactional`, `send bulk`, `send batch-transactional`, `send batch-bulk` |
-| **Sandbox** | `sandbox-send single`, `sandbox-send batch` |
 | **Domains** | `domains list`, `domains get`, `domains create`, `domains delete` |
 | **Templates** | `templates list`, `templates get`, `templates create`, `templates update`, `templates delete` |
 | **Suppressions** | `suppressions list`, `suppressions delete` |
 | **Stats** | `stats get`, `stats by-domain`, `stats by-category`, `stats by-esp`, `stats by-date` |
 | **Email Logs** | `email-logs list`, `email-logs get` |
+| **Contacts** | `contacts get`, `contacts create`, `contacts update`, `contacts delete`, `contacts import`, `contacts import-status`, `contacts export`, `contacts export-status`, `contacts create-event` |
+| **Contact Lists** | `contact-lists list`, `contact-lists get`, `contact-lists create`, `contact-lists update`, `contact-lists delete` |
+| **Contact Fields** | `contact-fields list`, `contact-fields get`, `contact-fields create`, `contact-fields update`, `contact-fields delete` |
+| **Sandbox** | `sandbox-send single`, `sandbox-send batch` |
 | **Projects** | `projects list`, `projects get`, `projects create`, `projects update`, `projects delete` |
 | **Inboxes** | `inboxes list`, `inboxes get`, `inboxes create`, `inboxes update`, `inboxes delete`, `inboxes clean`, `inboxes mark-read`, `inboxes reset-credentials`, `inboxes toggle-email-username`, `inboxes reset-email-username` |
 | **Messages** | `messages list`, `messages get`, `messages update`, `messages delete`, `messages forward`, `messages spam-score`, `messages html-analysis`, `messages headers`, `messages html`, `messages text`, `messages source`, `messages raw`, `messages eml` |
 | **Attachments** | `attachments list`, `attachments get` |
-| **Contacts** | `contacts get`, `contacts create`, `contacts update`, `contacts delete`, `contacts import`, `contacts import-status`, `contacts export`, `contacts export-status`, `contacts create-event` |
-| **Contact Lists** | `contact-lists list`, `contact-lists get`, `contact-lists create`, `contact-lists update`, `contact-lists delete` |
-| **Contact Fields** | `contact-fields list`, `contact-fields get`, `contact-fields create`, `contact-fields update`, `contact-fields delete` |
 | **Accounts** | `accounts list` |
 | **Account Access** | `account-access list`, `account-access remove` |
 | **Permissions** | `permissions resources`, `permissions bulk-update` |