feat: add common.sh file and initialize install.sh

scripts/common.sh

@@ -0,0 +1,17 @@
+#!/bin/bash
+
+FILENAME="serverconfig"
+
+ENV_DIR="/etc/$FILENAME"
+ENV_FILE="$ENV_DIR/.env"
+LOG="/var/log/$FILENAME.log"
+
+DATETIME_FORMAT="%d-%m-%Y %H:%M:%S"
+
+datetime_print() {
+    local message="$1"
+    local level="${2:-INFO}"
+    local timestamp="[$(date +"$DATETIME_FORMAT")]"
+
+    echo "$timestamp - $level: $message" | tee -a "$LOG"
+}