feat(account): Prioritize dedicated name field for IMAP authentication username #28

Refactor account authentication logic to prioritize the `name` field over the `email` field during the IMAP connection phase.

- The `name` field now serves as the primary IMAP login credential and is no longer treated purely as an optional, descriptive field.
- If the `name` field is empty or unset, the system will fall back to using the full `email` address for authentication.
- This change supports IMAP providers that require a username different from the full email address (e.g., employee ID, specific account name).

web/src/locales/nl.json

@@ -163,6 +163,7 @@
         "emailPlaceholder": "bv. john.doe@voorbeeld.com",
         "namePlaceholder": "bv. john.doe",
         "optional": "Optioneel",
+        "nameDescription": "IMAP-verbindingsgebruikersnaam. Laat dit veld leeg als u uw volledige e-mailadres als verbindingsgebruikersnaam gebruikt.",
         "emailCannotBeModified": "Het e-mailadres van het account kan niet worden gewijzigd tijdens het bewerken.",
         "addAccount": "Account Toevoegen",
         "updateAccount": "Account Bijwerken",