chore(deploy): 统一初始化 Dovecot 认证策略随机数

- 在部署入口脚本中生成并持久化 `auth_policy_hash_nonce`，避免每次启动变更。
- 同步更新 Dovecot 配置项为 `auth_policy_request_attributes`，并注入随机数值。

deploy/dovecot/dovecot.conf

@@ -23,7 +23,8 @@ auth_policy_server_url = http://127.0.0.1:8080/auth-policy
 auth_policy_server_api_header = Content-Type: application/json
 auth_policy_hash_mech = sha256
 auth_policy_hash_truncate = 12
-auth_policy_request_fields = protocol=imap username=user
+auth_policy_hash_nonce = __LANQIN_AUTH_POLICY_HASH_NONCE__
+auth_policy_request_attributes = protocol=imap username=user
 
 namespace inbox {
   inbox = yes

deploy/dovecot/entrypoint.sh

@@ -4,8 +4,15 @@ set -eu
 : "${LANQIN_TLS_KEY_FILE:=}"
 addgroup --system --gid 5000 vmail 2>/dev/null || true
 adduser --system --uid 5000 --gid 5000 --home /var/mail/vhosts --no-create-home vmail 2>/dev/null || true
-mkdir -p /var/mail/vhosts
+mkdir -p /data /var/mail/vhosts
 chown -R 5000:5000 /var/mail/vhosts
+AUTH_POLICY_NONCE_FILE="${LANQIN_AUTH_POLICY_NONCE_FILE:-/data/dovecot-auth-policy-nonce}"
+mkdir -p "$(dirname "$AUTH_POLICY_NONCE_FILE")"
+if [ ! -s "$AUTH_POLICY_NONCE_FILE" ]; then
+  od -An -tx1 -N32 /dev/urandom | tr -d ' \n' > "$AUTH_POLICY_NONCE_FILE"
+fi
+chmod 600 "$AUTH_POLICY_NONCE_FILE" 2>/dev/null || true
+AUTH_POLICY_HASH_NONCE="$(cat "$AUTH_POLICY_NONCE_FILE")"
 TLS_CERT=/etc/ssl/certs/ssl-cert-snakeoil.pem
 TLS_KEY=/etc/ssl/private/ssl-cert-snakeoil.key
 if [ -n "$LANQIN_TLS_CERT_FILE" ] || [ -n "$LANQIN_TLS_KEY_FILE" ]; then
@@ -18,4 +25,5 @@ if [ -n "$LANQIN_TLS_CERT_FILE" ] || [ -n "$LANQIN_TLS_KEY_FILE" ]; then
 fi
 sed -i "s#^ssl_cert = <.*#ssl_cert = <${TLS_CERT}#" /etc/dovecot/dovecot.conf
 sed -i "s#^ssl_key = <.*#ssl_key = <${TLS_KEY}#" /etc/dovecot/dovecot.conf
+sed -i "s#^auth_policy_hash_nonce = .*#auth_policy_hash_nonce = ${AUTH_POLICY_HASH_NONCE}#" /etc/dovecot/dovecot.conf
 exec dovecot -F