feat(agama): add control-flow code-generation conformance tests for the transpiler

**Is your feature request related to a problem? Please describe.**
The Agama transpiler's control-flow constructs (When/Otherwise, Match, Repeat/Quit When, Iterate) are exercised by
syntax-only pass tests, but nothing asserts that they generate the expected JavaScript control structures, so a
code-generation regression could go unnoticed.

**Describe the solution you'd like**
Add a test that transpiles a flow using all the control-flow constructs and asserts the generated code contains the
corresponding JS (conditional, equality-based match branches, counted loop, iteration loop, loop break).

**Describe alternatives you've considered**
Relying on the syntax-only pass tests — rejected: they don't verify code generation.

**Additional context**
Part of the effort to add semantic/spec-conformance coverage to the Agama subsystem; covers the
transpiler/code-generation side of the control-flow constructs (runtime evaluation is exercised by the engine's
end-to-end tests on a deployment).