feat: using config crate

src/main.rs

@@ -5,9 +5,11 @@ use weight_tracker::{AppState, create_app, config::Config};
 #[tokio::main]
 async fn main() {
     // Load configuration from config.toml or environment variables
-    let config = Config::load("config.toml").unwrap_or_else(|_| {
-        println!("config.toml not found, using environment variables");
-        Config::from_env()
+    // config-rs automatically merges file + environment + defaults
+    let config = Config::load("config.toml").unwrap_or_else(|e| {
+        eprintln!("Failed to load configuration: {}", e);
+        eprintln!("Using default values. Set environment variables prefixed with WEIGHT_TRACKER_ to override.");
+        std::process::exit(1);
     });
 
     // Set up database