Harden checks in `IsDisjointCoverNode` constructor

During construction, we could check that the upper and lower bounds on the total cardinality of the input "covering" sets/arrays do not immediately lead to a structural infeasibility.

Start at the IsDisjointCoverNode constructor and inspect how the upper and lower cardinality bounds are represented for covering sets or arrays. Trace the existing construction checks and determine how immediately structurally infeasible bounds are handled. Done means construction rejects those infeasible inputs while preserving valid cases; no test file is named in the issue.

Written by the indexing model from the issue text.