fix: discover existing MySQL client tools

scripts/test-install-fixture.sh

@@ -37,6 +37,7 @@ mode_of() {
   sed -n '/^release_asset_url()/,/^}/p' "$ROOT/deploy/install.sh"
   sed -n '/^download_release_asset()/,/^}/p' "$ROOT/deploy/install.sh"
   sed -n '/^install_packages()/,/^}/p' "$ROOT/deploy/install.sh"
+  sed -n '/^mysql_client_bin()/,/^}/p' "$ROOT/deploy/install.sh"
   sed -n '/^preflight_database()/,/^}/p' "$ROOT/deploy/install.sh"
   sed -n '/^secure_release_tree()/,/^}/p' "$ROOT/deploy/install.sh"
   sed -n '/^restore_unit_state()/,/^}/p' "$ROOT/deploy/install.sh"
@@ -47,6 +48,17 @@ source "$WORK/helpers.sh"
 export SETUP_WIZARD=true
 preflight_database || fail 'setup wizard database preflight returned a failure status'
 
+mkdir -p "$WORK/mysql-bin"
+cat > "$WORK/mysql-bin/mysql" <<'SH'
+#!/bin/sh
+exit 0
+SH
+chmod 0755 "$WORK/mysql-bin/mysql"
+export KAIDI_MYSQL_CLIENT="$WORK/mysql-bin/mysql"
+[ "$(mysql_client_bin)" = "$WORK/mysql-bin/mysql" ] \
+  || fail 'installer did not honor the explicit MySQL client path'
+unset KAIDI_MYSQL_CLIENT
+
 release_permissions="$WORK/release-permissions"
 mkdir -p "$release_permissions/public" "$release_permissions/ops"
 printf 'jar\n' > "$release_permissions/app.jar"
@@ -293,6 +305,8 @@ grep -Fq '32-bit Linux deployment requires the glibc loader' "$ROOT/deploy/insta
   || fail 'installer does not reject a 32-bit host without the glibc loader'
 grep -Fq 'preflight_runtime_commands' "$ROOT/deploy/install.sh" \
   || fail 'installer does not validate required runtime commands'
+grep -Fq 'KAIDI_MYSQLDUMP_BIN "${KAIDI_MYSQLDUMP_BIN:-}"' "$ROOT/deploy/install.sh" \
+  || fail 'installer does not preserve a custom mysqldump path for online updates'
 # shellcheck disable=SC2016 # Match literal installer source.
 grep -Fq 'write_env_file_preserving_unknown "$CONFIG_ROOT/kaidi.env"' "$ROOT/deploy/install.sh" \
   || fail 'installer no longer uses the reinstall-safe environment writer'
@@ -409,7 +423,7 @@ grep -Fq 'load_runtime_database_env' "$ROOT/deploy/update.sh" \
 # shellcheck disable=SC2016 # Match literal installer source.
 grep -Fq 'install -d -o root -g "$SERVICE_GROUP" -m 0750 "$UPDATE_STATE_ROOT"' "$ROOT/deploy/install.sh" \
   || fail 'update state parent is not group-accessible to the application user'
-grep -Fq 'kaidi-finance-1.0.0-preview.31.tar.gz' "$ROOT/README.md" \
+grep -Fq 'kaidi-finance-1.0.0-preview.34.tar.gz' "$ROOT/README.md" \
   || fail 'README does not document the public manual-deployment artifact'
 grep -Fq 'ops/baota-init.sh' "$ROOT/README.md" \
   || fail 'README does not document the local Baota initialization command'