Refactor codebase for consistency and readability

- Standardize array and vector formatting for clarity.
- Adjust spacing and indentation in examples and TUI code.
- Ensure proper newline usage across files (e.g., LICENSE, TOML files, etc.).
- Simplify `.to_string()` and `.ok()` calls for brevity.

examples/custom_provider.rs

@@ -16,10 +16,16 @@ impl Provider for MyCustomProvider {
     }
 
     async fn chat(&self, session: &Session, model: &Model) -> Result<String, anyhow::Error> {
-        println!("Custom provider received chat request for model: {}", model.name);
+        println!(
+            "Custom provider received chat request for model: {}",
+            model.name
+        );
         // In a real implementation, you would send the session data to an API.
         let message_count = session.get_messages().len();
-        Ok(format!("This is a custom response. You have {} messages in your session.", message_count))
+        Ok(format!(
+            "This is a custom response. You have {} messages in your session.",
+            message_count
+        ))
     }
 }