Refactor Record and List to use TupleData

The `Value::List` and `Value::Record` variants have been consolidated
into a single `Value::Tuple` variant. This new variant uses a
`TupleData` struct to store values and an optional `Rc<Vec<Keyword>>`
for keys, allowing it to represent both ordered lists/tuples and
key-value records.

This change simplifies the internal representation and improves
performance by allowing schema sharing for records. It also includes
updates to the compiler, runtime, and tests to reflect the new
structure.

src/utils/tester.rs

@@ -66,11 +66,11 @@ pub fn run_functional_tests() -> Vec<TestResult> {
 pub fn run_benchmarks(update: bool) -> Vec<BenchmarkResult> {
     let mut results = Vec::new();
     let entries = fs::read_dir("examples").unwrap();
-    let env = Environment::new();
     let is_release = !cfg!(debug_assertions);
     let baseline_re = Regex::new(r";; Benchmark: ([\d\.]+\w+)").unwrap();
 
     for entry in entries.filter_map(|e| e.ok()) {
+        let env = Environment::new(); // Fresh environment per benchmark for isolation
         let path = entry.path();
         if path.extension().is_some_and(|ext| ext == "myc") {
             let content = fs::read_to_string(&path).unwrap();
@@ -81,7 +81,16 @@ pub fn run_benchmarks(update: bool) -> Vec<BenchmarkResult> {
             // Prepare: Compile and Link once outside the measurement loop
             let linked_node = match env.compile(&content).map(|c| env.link(c)) {
                 Ok(node) => node,
-                Err(_) => continue, // Skip scripts that don't compile
+                Err(e) => {
+                    results.push(BenchmarkResult {
+                        name,
+                        median: Duration::ZERO,
+                        baseline: None,
+                        diff_pct: None,
+                        status: format!("COMPILE ERROR: {}", e),
+                    });
+                    continue;
+                }
             };
 
             // Measure: Only the VM execution