feat: add config for mail server name (#13632)

fix #13627

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

* **New Features**
* Added configurable display names for primary and fallback SMTP
servers, improving email sender identification.
* Defaults to “AFFiNE Server,” with support for MAILER_SERVERNAME
environment variable for the primary SMTP.
* Exposed in admin settings for easy setup alongside existing SMTP
options.
* Names are now passed through to mail transport options for consistent
use across emails.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

.docker/selfhost/schema.json

@@ -195,6 +195,11 @@
       "type": "object",
       "description": "Configuration for mailer module",
       "properties": {
+        "SMTP.name": {
+          "type": "string",
+          "description": "Name of the email server (e.g. your domain name)\n@default \"AFFiNE Server\"\n@environment `MAILER_SERVERNAME`",
+          "default": "AFFiNE Server"
+        },
         "SMTP.host": {
           "type": "string",
           "description": "Host of the email server (e.g. smtp.gmail.com)\n@default \"\"\n@environment `MAILER_HOST`",
@@ -230,6 +235,11 @@
           "description": "The emails from these domains are always sent using the fallback SMTP server.\n@default []",
           "default": []
         },
+        "fallbackSMTP.name": {
+          "type": "string",
+          "description": "Name of the fallback email server (e.g. your domain name)\n@default \"AFFiNE Server\"",
+          "default": "AFFiNE Server"
+        },
         "fallbackSMTP.host": {
           "type": "string",
           "description": "Host of the email server (e.g. smtp.gmail.com)\n@default \"\"",