chore(deploy): 调整 rspamd 与 dovecot 启动配置

- 为 `rspamd` 指定运行用户/组，提升容器内启动一致性。
- 将 `dovecot` 配置格式整理为多行块，保持配置可读性。
- 在 `rspamd` 入口脚本中按可用账号选择启动参数，并保留兜底启动方式。

deploy/dovecot/dovecot.conf

@@ -12,11 +12,21 @@ ssl_key = </etc/ssl/private/ssl-cert-snakeoil.key
 mail_home = /var/mail/vhosts/%d/%n
 namespace inbox {
   inbox = yes
-  mailbox Drafts { special_use = \Drafts }
-  mailbox Sent { special_use = \Sent }
-  mailbox Trash { special_use = \Trash }
-  mailbox Archive { special_use = \Archive }
-  mailbox Spam { special_use = \Junk }
+  mailbox Drafts {
+    special_use = \Drafts
+  }
+  mailbox Sent {
+    special_use = \Sent
+  }
+  mailbox Trash {
+    special_use = \Trash
+  }
+  mailbox Archive {
+    special_use = \Archive
+  }
+  mailbox Spam {
+    special_use = \Junk
+  }
 }
 
 passdb {
@@ -29,11 +39,17 @@ userdb {
 }
 
 service imap-login {
-  inet_listener imaps { port = 993 ssl = yes }
+  inet_listener imaps {
+    port = 993
+    ssl = yes
+  }
 }
 
 service lmtp {
-  inet_listener lmtp { address = 0.0.0.0 port = 24 }
+  inet_listener lmtp {
+    address = 0.0.0.0
+    port = 24
+  }
 }
 
 service auth {