Function detect 

pub fn detect(
    unit: &FnUnit<'_>,
    imports: &Imports,
    span: &SpanIndex<'_>,
    path: &str,
) -> Vec<RiskFeature>

Detect dynamic-code risk features in unit’s own body.

path is the source file path to embed in each emitted RiskFeature.

Returns a Vec<RiskFeature> for each dangerous dynamic-code pattern found. The type.escape risk is intentionally NOT detected here — it is owned by the coverage gate in analyze_unit.