generate internal id (debugging only)

NOT set to provider... Anthropic will reject a message with id

examples/verify_message_id.rs

@@ -0,0 +1,32 @@
+// Verification script to demonstrate Message ID implementation
+// Run with: cargo run --example verify_message_id
+
+use g3_providers::{Message, MessageRole};
+
+fn main() {
+    println!("=== Message ID Implementation Verification ===");
+    println!();
+    
+    // Create several messages to show ID generation
+    println!("Creating 5 messages to demonstrate ID generation:");
+    for i in 1..=5 {
+        let msg = Message::new(MessageRole::User, format!("Test message {}", i));
+        println!("  Message {}: id = '{}'", i, msg.id);
+    }
+    
+    println!();
+    println!("ID Format: HHMMSS-XXX");
+    println!("  - HHMMSS: Current time (hours, minutes, seconds)");
+    println!("  - XXX: 3 random alphabetic characters (a-z, A-Z)");
+    
+    println!();
+    println!("Verifying ID is NOT serialized to JSON:");
+    let msg = Message::new(MessageRole::User, "Hello World".to_string());
+    let json = serde_json::to_string(&msg).unwrap();
+    println!("  Message ID: {}", msg.id);
+    println!("  JSON output: {}", json);
+    println!("  Contains 'id' field: {}", json.contains("\"id\""));
+    
+    println!();
+    println!("✅ Implementation complete!");
+}