Approximate economic viability contstraint

We can approximate the economic viability constraint by checking the traded amounts in the transitive orders against connected OWL limit prices. We would then discard any transitive orders that do not satisfy these constraints.

The issue names no files, tests, or entry points. Start by locating transitive-order handling and the checks for connected OWL limit prices, then determine how traded amounts and economic viability are represented. Done means invalid transitive orders are discarded when they fail the proposed constraints, with coverage for the relevant cases.

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