Breaking Change

Replace self. with this. in method bodies for instance self-reference.

Features

• Add this keyword for instance self-reference (DOL 2.0)
• Add Expr::This AST variant with full compiler support
• Update all example files to use this.field/this.method() syntax
• WASM compiler stub for this (full support coming later)

Design Rationale

Chose this over self because:

1. Differentiates DOL from Rust's self conventions
2. Broader familiarity (JS, Java, C++, C#, TypeScript)
3. Emphasizes genes as domain objects, not implementation structs

Note: Self remains as the type-level self-reference (standard convention).

Migration

- self.value
+ this.value

- self.method()
+ this.method()