graph: outputs of inline DAG calls have no dependency edges #2078

Found in the review of #2057, which adds the experimental view. #2059 fixed how the view handles inline dag declarations, but left this gap, which graphcal graph shares.

Problem

A node that reads an output of an inline DAG call has no dependency on it. The graph IR has no instances for DAG calls, so neither graphcal graph nor the view model can draw the edge.

dag checked {
    param v: Dimensionless;
    pub node out: Dimensionless = @v * 2.0;
}
node out: Dimensionless = @checked(v: 3.0)::out;
include checked(v: 4.0) as also_fine;
node z: Dimensionless = @out + @also_fine::out;

• graphcal graph draws the include also_fine as a cluster with an edge into z, but the root out has no incoming edge.
• In graphcal view, the root out's deps is empty.

Proposed fix

• Represent each DAG call's instance in the graph IR, as includes are.
• Show the outputs it reads as external nodes in the view model, and as edges in graphcal graph.