fix: emit Fixed event when bound tightening collapses a gapped domain

Tightening a bound on a gapped domain (e.g. {3,5} to max 4 -> {3}) can
fix a variable even when the bound value differs from the opposite bound.
The old Model notification logic missed this, so value-based propagators
were never notified.

chore: Release package huub version 100.1.0

chore: release v100.0.0

solver version used to conduct the experiment for the CP2025 paper