improve: dependent types review — cycle detection, precision, error quality
- Fix ast_to_pred_expr silent Value fallback → opaque Call prevents false positives
- check_refinement now handles BoolLit/StringLit with human-readable display
- Integer equality/inequality uses exact i64 via try_resolve_ints (no f64 loss)
- Type::Refined handled in unwrap_reactive + new unwrap_refined() utility
- Type alias cycle detection via type_expr_references in Pass 0
- 9 new tests: predicate display, evaluate_static (int/compound/eq_precision),
unwrap_refined, refined type display, cycle detection, readable violations
127 workspace tests pass (25 in ds-types), 0 failures
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