Function try_region 

pub fn try_region(
    src: &str,
    fn_name: &str,
    target: &AnalogTarget,
) -> Result<(RegionLane, AnalogArtifact), AnaLowerError>

Try to compile ONE region function on target, deciding the lane from its parameter family: float params → the ε-certified pipeline; else the certified-exact integer pipeline. PANIC-SAFE: extraction shapes outside the supported family become a typed refusal, never a crash — this is the entry the mixed-signal partition (and compile_to_analog) dispatches through for arbitrary programs.