Post-review: kill duplicated magic constants by making them authored data

A code review of an emergent-sim refactor flagged an altitude smell: the advantage magnitude of an adopted capability was hardcoded as the same two constants (distance=1, condition=0.9) in two files that had to stay in sync by hand — which quietly reintroduced the very knob the refactor set out to remove. Fix: move the constants onto the content object (the capability spec) as authored attrs with engine defaults, so both the ROI calc and the created edge read one source and a world can override. Second gotcha the reviewers caught: a graph/edge lookup that ignores medium returns the first-created edge, so when two nodes are linked by multiple media, an operators own cheaper lane is invisible and its capability-gated cost never applies — enumerate all edges and filter by what the operator can traverse (media AND scale).