feat: 支持SSH密钥认证，REMOTE_KEY配置项

- 新增 _ssh_wrap 辅助函数：有key用key，有密码用sshpass，都没有走默认
- save_config 新增 REMOTE_KEY 字段
- setup 交互新增密钥路径提示
- sshpass 依赖改为可选（key认证不需要）

vps-snapshot.sh

@@ -54,7 +54,7 @@ install_deps() {
 check_deps() {
     local missing=""
     command -v rsync &>/dev/null || missing+=" rsync"
-    command -v sshpass &>/dev/null || missing+=" sshpass"
+    # sshpass is optional when using key auth
     command -v jq &>/dev/null || missing+=" jq"
     
     if [ -n "$missing" ]; then
@@ -631,7 +631,7 @@ cleanup_remote() {
     local remote_path="${REMOTE_DIR:-/backup}/${VPS_NAME:-$(hostname)}"
     
     log "🧹 清理远程旧快照 (保留${days}天)..."
-    sshpass -p "$REMOTE_PASS" ssh -o StrictHostKeyChecking=no \
+    _ssh_wrap ssh -o StrictHostKeyChecking=no \
         -p "${REMOTE_PORT:-22}" "${REMOTE_USER:-root}@$REMOTE_IP" \
         "find $remote_path -name '*.tar.gz' -mtime +$days -delete 2>/dev/null" || true
 }
@@ -883,7 +883,7 @@ do_restore_config_remote() {
     echo ""
     
     # 获取远程快照列表
-    local snap_list=$(sshpass -p "$REMOTE_PASS" ssh -o StrictHostKeyChecking=no \
+    local snap_list=$(_ssh_wrap ssh -o StrictHostKeyChecking=no \
         -p "${REMOTE_PORT:-22}" "${REMOTE_USER:-root}@$REMOTE_IP" \
         "ls -t $remote_path/*.tar.gz 2>/dev/null")
     
@@ -895,7 +895,7 @@ do_restore_config_remote() {
     local snaps=()
     while read -r snap; do
         local name=$(basename "$snap")
-        local size=$(sshpass -p "$REMOTE_PASS" ssh -o StrictHostKeyChecking=no \
+        local size=$(_ssh_wrap ssh -o StrictHostKeyChecking=no \
             -p "${REMOTE_PORT:-22}" "${REMOTE_USER:-root}@$REMOTE_IP" \
             "ls -lh '$snap' 2>/dev/null | awk '{print \$5}'" 2>/dev/null)
         echo "  $i) $name ($size)"
@@ -916,7 +916,7 @@ do_restore_config_remote() {
     
     log "下载快照: $(basename "$selected")"
     local local_file="/tmp/remote_snapshot_$$.tar.gz"
-    sshpass -p "$REMOTE_PASS" scp -o StrictHostKeyChecking=no \
+    _ssh_wrap scp -o StrictHostKeyChecking=no \
         -P "${REMOTE_PORT:-22}" "${REMOTE_USER:-root}@$REMOTE_IP:$selected" "$local_file"
     
     [ ! -f "$local_file" ] && { error "下载失败"; return 1; }
@@ -1012,12 +1012,12 @@ do_sync_remote() {
     log "📤 同步到远程: $REMOTE_IP:$remote_path"
     
     # 创建远程目录（以VPS名称命名）
-    sshpass -p "$REMOTE_PASS" ssh -o StrictHostKeyChecking=no \
+    _ssh_wrap ssh -o StrictHostKeyChecking=no \
         -p "${REMOTE_PORT:-22}" "${REMOTE_USER:-root}@$REMOTE_IP" \
         "mkdir -p $remote_path"
     
     # 同步到VPS专属目录
-    sshpass -p "$REMOTE_PASS" rsync -avz --progress \
+    _ssh_wrap rsync -avz --progress \
         -e "ssh -o StrictHostKeyChecking=no -p ${REMOTE_PORT:-22}" \
         "$latest" "${REMOTE_USER:-root}@$REMOTE_IP:$remote_path/"
     
@@ -1140,6 +1140,31 @@ load_config() {
     [ -f "$CONFIG_FILE" ] && source "$CONFIG_FILE"
 }
 
+# SSH/SCP/rsync 前缀：有key用key，有密码用sshpass，都没有走默认
+_ssh_wrap() {
+    local mode="$1"; shift
+    local key="${REMOTE_KEY:-}" pass="${REMOTE_PASS:-}"
+    if [ -n "$key" ] && [ -f "$key" ]; then
+        case "$mode" in
+            ssh)  ssh -i "$key" "$@" ;;
+            scp)  scp -i "$key" "$@" ;;
+            rsync) rsync -e "ssh -i $key" "$@" ;;
+        esac
+    elif [ -n "$pass" ]; then
+        case "$mode" in
+            ssh)  sshpass -p "$pass" ssh "$@" ;;
+            scp)  sshpass -p "$pass" scp "$@" ;;
+            rsync) sshpass -p "$pass" rsync "$@" ;;
+        esac
+    else
+        case "$mode" in
+            ssh)  ssh "$@" ;;
+            scp)  scp "$@" ;;
+            rsync) rsync "$@" ;;
+        esac
+    fi
+}
+
 save_config() {
     cat > "$CONFIG_FILE" << EOF
 VPS_NAME="$VPS_NAME"
@@ -1149,6 +1174,7 @@ REMOTE_IP="$REMOTE_IP"
 REMOTE_PORT="$REMOTE_PORT"
 REMOTE_USER="$REMOTE_USER"
 REMOTE_PASS="$REMOTE_PASS"
+REMOTE_KEY="$REMOTE_KEY"
 REMOTE_DIR="$REMOTE_DIR"
 REMOTE_KEEP_DAYS="$REMOTE_KEEP_DAYS"
 TG_BOT_TOKEN="$TG_BOT_TOKEN"
@@ -1179,8 +1205,9 @@ do_setup() {
         REMOTE_PORT=${REMOTE_PORT:-22}
         read -p "远程用户 [root]: " REMOTE_USER
         REMOTE_USER=${REMOTE_USER:-root}
-        read -s -p "远程密码: " REMOTE_PASS
+        read -s -p "远程密码 (key认证留空): " REMOTE_PASS
         echo ""
+        read -p "远程密钥路径 (密码认证留空): " REMOTE_KEY
         read -p "远程目录 [/backup]: " REMOTE_DIR
         REMOTE_DIR=${REMOTE_DIR:-/backup}
         read -p "远程保留天数 [30]: " REMOTE_KEEP_DAYS