Refactor: Implement Record Layouts and Optimized Field Access

Introduces a new `RecordLayout` system for efficient and type-safe
record handling.

Key changes:
- `RecordLayout` struct with `O(1)` field lookup using FMap
  optimization.
- Field accessors (`.name`) are now first-class callable values.
- Parser recognizes dot-prefixed identifiers as field accessors.
- Binder and TypeChecker handle field accessors.
- Optimizer transforms field accessor calls into specialized `GetField`
  nodes.
- VM executes `GetField` efficiently by directly accessing record
  values.
- Adds a new `records.myc` example showcasing record features.
- Improves comparison logic for records to use pointer equality for
  layout.

src/ast/parser.rs

@@ -100,6 +100,9 @@ impl<'a> Parser<'a> {
             TokenKind::Keyword(k) => UntypedKind::Constant(Value::Keyword(Keyword::intern(&k))),
             TokenKind::Identifier(id) => match id.as_ref() {
                 "..." => UntypedKind::Nop,
+                s if s.starts_with('.') && s.len() > 1 => {
+                    UntypedKind::FieldAccessor(Keyword::intern(&s[1..]))
+                }
                 _ => UntypedKind::Identifier(id.into()),
             },
             _ => {