Phase 6 features:
- ForIn reactive list rendering: for item in items -> body
- Optional index binding: for item, idx in items -> body
- Component declarations: component Name(props) = body
- Component instantiation: ComponentUse { name, props }
Added across 5 crates:
- ds-parser: For/In/Component tokens, ForIn/ComponentDecl AST nodes
- ds-codegen: reactive list effect, component function emission
- ds-types: ForIn/ComponentUse type inference
- local_vars tracking for non-reactive for-in loop vars
Includes examples/list.ds showcasing for-in + when + signals.
