Update setup docs and scripts

Refresh setup docs, add ZXDB local setup script, and note deploy rules.

Signed-off-by: codex@lucy.xalior.com

bin/setup-zxdb-local.sh

@@ -0,0 +1,18 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+git_dir="$(git -C ZXDB rev-parse --git-dir)"
+exclude_file="${git_dir}/info/exclude"
+
+mkdir -p "$(dirname "${exclude_file}")"
+touch "${exclude_file}"
+
+add_exclude() {
+  local pattern="$1"
+  if ! grep -Fxq "${pattern}" "${exclude_file}"; then
+    printf "%s\n" "${pattern}" >> "${exclude_file}"
+  fi
+}
+
+add_exclude "ZXDB_mysql.sql"
+add_exclude "ZXDB_mysql_STRUCTURE_ONLY.sql"