feat: add Nginx to Caddy migration toolkit with scripts and usage guide

setup/nginx-to-caddy/lib.sh

@@ -0,0 +1,51 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+if [[ -t 2 ]]; then
+  _C_RESET='\033[0m'
+  _C_RED='\033[0;31m'
+  _C_GREEN='\033[0;32m'
+  _C_YELLOW='\033[0;33m'
+  _C_BLUE='\033[0;34m'
+else
+  _C_RESET='' _C_RED='' _C_GREEN='' _C_YELLOW='' _C_BLUE=''
+fi
+
+log_info() {
+  printf '%b[INFO]%b %s\n' "$_C_BLUE" "$_C_RESET" "$*" >&2
+}
+
+log_warn() {
+  printf '%b[WARN]%b %s\n' "$_C_YELLOW" "$_C_RESET" "$*" >&2
+}
+
+log_error() {
+  printf '%b[ERROR]%b %s\n' "$_C_RED" "$_C_RESET" "$*" >&2
+}
+
+log_success() {
+  printf '%b[OK]%b %s\n' "$_C_GREEN" "$_C_RESET" "$*" >&2
+}
+
+require_cmd() {
+  local cmd
+  for cmd in "$@"; do
+    if ! command -v "$cmd" >/dev/null 2>&1; then
+      log_error "Required command not found: $cmd"
+      return 1
+    fi
+  done
+}
+
+confirm_action() {
+  local prompt="${1:-Continue?}"
+  local auto_yes="${2:-false}"
+
+  if [[ "$auto_yes" == "true" ]]; then
+    return 0
+  fi
+
+  printf '%s [y/N] ' "$prompt"
+  read -r reply
+  [[ "$reply" =~ ^[Yy]$ ]]
+}