This mini-fixture demonstrates the `forbid_function_call` matcher of the
rustqual Architecture dimension.
Symbols configured in `forbid_function_call` are matched against the
**full rendered path** of call expressions. `forbid_function_call =
["Box::new"]` matches `Box::new(x)` but not `Thing::new()` and not
`x.new()` (the latter is a method call — `forbid_method_call` territory).
`src/domain/bad.rs` contains a single-call violation — the domain layer
constructing a `Box<T>` via `Box::new`. The expected finding:
- ---
The AST-level matcher `find_function_call_matches` when run against
`src/domain/bad.rs` with path `"Box::new"` returns exactly **one**
`MatchLocation` whose `ViolationKind::FunctionCall.rendered_path ==
"Box::new"`.