Replace the TODO-marked manual if-else logic in `Strength.weakest` and `Strength.strongest` with the ternary operator, and refactor the manual while-loop list filtering in `Variable.removeConstraint` to use the `.where()` method for cleaner, more idiomatic Wren code.
In the compiler, when a bare name is encountered inside a class definition and it does not resolve to a local variable or global, emit an implicit `this.` load before the call, enabling getter, setter, and method calls without explicit receiver. Update all benchmark, builtin, and test files to remove redundant `this.` qualifiers, and add comprehensive test suites for implicit receiver behavior across instance, inherited, static, nested, and shadowing scenarios.
Add the DeltaBlue constraint-solving benchmark ported from Dart to Wren, along with supporting Lua and Python versions for cross-validation. The Wren implementation includes the full constraint hierarchy solver with strength classes, plan execution, and the standard DeltaBlue test harness. Register the benchmark in run_bench with expected output "7032700".
