UnaryMathConverter

Converter for elementwise unary math operations that map 1:1 onto a StableHLO primitive.

Without these, traced graphs that use sqrt/exp/abs/… fall through to the "no converter found" path in sk.ainet.compile.hlo.StableHloConverter. Because that path never calls context.setValueName, downstream consumers of the failed node lose an operand via the mapNotNull in processNode, and appear to the next converter as if they had "wrong arity". A single missing unary converter therefore cascades many unrelated "Unsupported X arity" errors further down the graph — which is most of what the Whisper upstream-issues doc calls "Issue B".