Add migration scripts and other fixes

migration/export-docker-mailserver.sh

@@ -0,0 +1,29 @@
+#!/usr/bin/env bash
+# Dumps accounts + aliases from a docker-mailserver config directory into a
+# migration CSV skeleton (email,new_password,old_password,aliases,quota_mb).
+# Passwords are left blank: docker-mailserver only stores irreversible hashes.
+set -euo pipefail
+
+CONFIG_DIR="${1:?Usage: $0 /path/to/docker-mailserver/config}"
+ACCOUNTS_FILE="$CONFIG_DIR/postfix-accounts.cf"
+ALIASES_FILE="$CONFIG_DIR/postfix-virtual.cf"
+
+if [[ ! -f "$ACCOUNTS_FILE" ]]; then
+  echo "postfix-accounts.cf not found under $CONFIG_DIR" >&2
+  exit 1
+fi
+
+echo "email,new_password,old_password,aliases,quota_mb"
+
+while IFS='|' read -r email _hash; do
+  [[ -z "$email" || "$email" == \#* ]] && continue
+
+  aliases=""
+  if [[ -f "$ALIASES_FILE" ]]; then
+    # postfix-virtual.cf lines look like: alias@domain destination@domain
+    aliases=$(awk -v dest="$email" '$2 == dest { sub(/@.*/, "", $1); printf "%s;", $1 }' "$ALIASES_FILE")
+    aliases="${aliases%;}"
+  fi
+
+  echo "$email,,,${aliases},"
+done < "$ACCOUNTS_FILE"