feat: Implement Pipeline support

Adds support for pipelines, allowing streams to be chained together and
transformed.
This includes new types for `PipeStream` and `SourceAdapter`, along with
modifications
to the `Environment` to manage pipeline execution. A new example
`pipeline.myc`
demonstrates its usage.

src/ast/vm.rs

@@ -395,14 +395,28 @@ impl VM {
                     return Err("Pipe lambda must be a function/closure".to_string());
                 };
 
+                // Create the persistent execution closure for the PipeStream
+                let mut pipe_vm = crate::ast::vm::VM::new(self.globals.clone());
+                let my_closure = lambda_obj.clone();
+                let executor: Box<dyn FnMut(Vec<Value>) -> Value> = Box::new(move |args: Vec<Value>| -> Value {
+                    match pipe_vm.run_with_args(my_closure.clone(), args) {
+                        Ok(res) => res,
+                        Err(e) => panic!("Pipeline lambda execution failed: {}", e),
+                    }
+                });
+
                 let pipe = Rc::new(RefCell::new(PipeStream::new(
                     "pipe".to_string(),
                     inputs.len(),
-                    Some(lambda_obj)
+                    Some(executor)
                 )));
 
-                for stream in obs_streams {
-                    stream.add_observer(pipe.clone() as Rc<RefCell<dyn crate::ast::rtl::streams::Observer>>);
+                for (i, stream) in obs_streams.into_iter().enumerate() {
+                    let adapter = Rc::new(RefCell::new(crate::ast::rtl::streams::SourceAdapter {
+                        target: pipe.clone() as Rc<RefCell<dyn crate::ast::rtl::streams::Observer>>,
+                        target_index: i,
+                    }));
+                    stream.add_observer(adapter);
                 }
 
                 // Create the data buffer and pusher for the pipe's output