evaluateComponentTree
Evaluates one component callback without installing a profile runtime.
This privileged bridge exists for runtime adapters and structural conformance tests that already own raw Element descriptions. Application screens use dev.s7a.strata.screen.ScreenDefinition, which evaluates its root implicitly. Profile-backed components fail unless an enclosing runtime evaluation is already active on the current thread.
Return
the exact emitted root element.
Parameters
content
callback that must emit exactly one root.
Throws
when content emits zero or multiple roots.