Feat: Add Pipe Node

Introduces a new `Pipe` node to the Abstract Syntax Tree (AST).
This node represents a functional composition pattern, allowing
for chaining of operations.

The changes include:
- Defining the `Pipe` variant in `BoundKind` and `UntypedKind`.
- Implementing parsing logic for the `pipe` keyword.
- Adding handling for the `Pipe` node in various compiler passes
  (analyzer, binder, captures, dumper, macros, optimizer, TCO,
  type checker).
- Including a placeholder implementation for `Pipe` execution in the
  VM.
- Updating integration tests to use the new `pipe` syntax.

src/ast/vm.rs

@@ -368,6 +368,17 @@ impl VM {
                     Ok(Value::Void)
                 }
             }
+            BoundKind::Pipe { inputs, lambda } => {
+                // To be implemented in next step:
+                // 1. Create PipeStream
+                // 2. Link with RootStream and Inputs
+                // 3. Create and return SharedSeries
+                for input in inputs {
+                    self.eval_internal(obs, input)?;
+                }
+                self.eval_internal(obs, lambda)?;
+                Ok(Value::Void)
+            }
             BoundKind::Block { exprs } => {
                 let mut last = Value::Void;
                 for e in exprs {