Addition of features and bug fixes.

[FernandoTheDev]

Add foreach, negative indexing, and stdlib polish

Language Features

• foreach statement: Support for value iteration (foreach v; arr), index + value (foreach k, v; arr), and by-reference (foreach &v; arr). Desugars to zero-cost C for loops using __typeof__ for element type inference.
• Negative indexing in ranges: arr[-3..size] now desugars to arr[size-3..size] at compile time.
• Multi-variable declarations: int x, y = 2, 7; syntax with arity checking.
• Polymorphic === operator: Now works with any struct that exposes a cmp method, not just strings.

Type System

• Contextual reference in type resolver: Enables anon dot syntax (.new(), .{}, .Bar) to work correctly in return statements and function call arguments by tracking the expected type through the call stack.
• Multi AST node: Handles multi-variable declarations cleanly in the parser pipeline.

Standard Library

• Renamed delete() → free() across HashMap, Array, Slice, String for consistency.
• Renamed compare() → cmp() in Slice for shorter method names.
• Migrated all stdlib examples to use anon dot syntax (.new(), .of(), .create()).
• Added std.iterator with generic Iterator<T> struct.

Housekeeping

• Moved examples/std/ → examples/stdlib/ for clearer naming.