fix: discover existing MySQL client tools

deploy/install.sh

@@ -230,6 +230,31 @@ preflight_runtime_commands() {
   done
 }
 
+mysql_client_bin() {
+  local candidate
+  if [ -n "${KAIDI_MYSQL_CLIENT:-}" ]; then
+    case "$KAIDI_MYSQL_CLIENT" in
+      */*) [ -x "$KAIDI_MYSQL_CLIENT" ] && printf '%s\n' "$KAIDI_MYSQL_CLIENT" && return 0 ;;
+      *) candidate=$(command -v "$KAIDI_MYSQL_CLIENT" 2>/dev/null || true); [ -n "$candidate" ] && printf '%s\n' "$candidate" && return 0 ;;
+    esac
+    return 1
+  fi
+  candidate=$(command -v mysql 2>/dev/null || command -v mariadb 2>/dev/null || true)
+  if [ -n "$candidate" ]; then
+    printf '%s\n' "$candidate"
+    return 0
+  fi
+  for candidate in \
+    /www/server/mysql/bin/mysql /www/server/mysql/bin/mariadb \
+    /usr/bin/mysql /usr/bin/mariadb /usr/local/mysql/bin/mysql /opt/mysql/bin/mysql; do
+    if [ -x "$candidate" ]; then
+      printf '%s\n' "$candidate"
+      return 0
+    fi
+  done
+  return 1
+}
+
 azul_arch() {
   case "${HOST_ARCH:-$(normalized_host_arch)}" in
     x86_64) printf x86 ;;
@@ -617,8 +642,8 @@ preflight_database() {
     jdbc:mysql://*) ;;
     *) die "KAIDI_DB_URL must start with jdbc:mysql://" ;;
   esac
-  client=$(command -v mysql || command -v mariadb || true)
-  [ -n "$client" ] || die "A MySQL command-line client is required"
+  client=$(mysql_client_bin || true)
+  [ -n "$client" ] || die "A MySQL command-line client is required; set KAIDI_MYSQL_CLIENT or add mysql/mariadb to PATH"
   host=$(database_host)
   port=$(database_port)
   name=$(database_name)
@@ -1000,7 +1025,8 @@ write_env_file "$CONFIG_ROOT/update.env" \
   KAIDI_DB_PORT "$(database_port)" \
   KAIDI_DB_NAME "$(database_name)" \
   KAIDI_DB_USERNAME "$DB_USERNAME" \
-  KAIDI_DB_PASSWORD "$DB_PASSWORD"
+  KAIDI_DB_PASSWORD "$DB_PASSWORD" \
+  KAIDI_MYSQLDUMP_BIN "${KAIDI_MYSQLDUMP_BIN:-}"
 chmod 0600 "$CONFIG_ROOT/update.env"
 
 install -m 0644 "$RELEASE_DIR/ops/kaidi-finance.service" /etc/systemd/system/kaidi-finance.service