Update runner to use engine factory pattern with Rhai packages

- Reverted from generic Package approach to factory function pattern
- Factory creates Engine::new_raw() + registers package (efficient)
- AsyncRunner and SyncRunner use engine_factory: Arc<dyn Fn() -> Engine>
- Each job gets a fresh engine instance (cheap with factory pattern)
- Package is created once inside factory, engines reuse it

src/sync_runner.rs

@@ -1,9 +1,8 @@
 use crate::job::Job;
-use log::{debug, error, info};
-use rhai::{Dynamic, Engine};
-use std::sync::Arc;
-
 use crate::runner_trait::Runner;
+use log::{debug, error, info};
+use rhai::{Engine, Dynamic};
+use std::sync::Arc;
 
 /// Configuration for sync runner instances
 #[derive(Debug, Clone)]
@@ -73,7 +72,7 @@ impl Runner for SyncRunner {
         debug!("Sync Runner '{}', Job {}: Processing started.", runner_id, job_id);
         info!("Sync Runner '{}' processing job_id: {}. Script: {:.50}...", job.context_id, job_id, job.payload);
         
-        // Create a new engine instance for this job execution
+        // Create a new engine instance (cheap with factory pattern)
         let mut engine = (self.engine_factory)();
         
         // Execute the script