feat: modularize scripts and improve project architecture

- Added `lib/utils.sh` and `lib/logging.sh` for reusable utility and logging functions.
- Updated `run.sh` and `scripts/generate-changelog.sh` to use the new utility and logging functions (`validate_arg`, `log_info`, `log_error`).
- Add `config.env` for better clarity and updated all references in the project.
- Enhanced documentation in `README.md` to reflect the new configuration file and usage instructions.
- Improved error handling and logging consistency across scripts.

lib/logging.sh

@@ -0,0 +1,29 @@
+#!/usr/bin/env bash
+# logging.sh - Logging functions for the project
+
+# Log levels
+LOG_LEVEL_INFO="INFO"
+LOG_LEVEL_WARN="WARN"
+LOG_LEVEL_ERROR="ERROR"
+
+# Function to log a message with a specific level
+log_message() {
+  local level="$1"
+  local message="$2"
+  local timestamp
+  timestamp=$(date +"%Y-%m-%d %H:%M:%S")
+  echo "[$timestamp] [$level] $message"
+}
+
+# Convenience functions for specific log levels
+log_info() {
+  log_message "$LOG_LEVEL_INFO" "$1"
+}
+
+log_warn() {
+  log_message "$LOG_LEVEL_WARN" "$1"
+}
+
+log_error() {
+  log_message "$LOG_LEVEL_ERROR" "$1"
+}