ekohan/fleetmix: v1.1.0: R1 paper revision + Henke heterogeneous experiment

Revision-round release accompanying the R1 resubmission of "Designing Multi-Compartment Last-Mile Vehicle Fleets". Highlights Exhaustive-enumeration validation pipeline — full subset enumeration for small instances, enabling optimality-gap analysis vs. the matheuristic. Henke heterogeneous benchmark runner — reproduces the heterogeneous fleet experiments requested by reviewers (n=10 and n=15). Cache-correctness fix — merged-cluster route-time cache now keys on customer coordinates, not just IDs, eliminating silent stale-hit corruption across benchmark instances with reused IDs. Paper revisions — updated manuscript, figures, and references for the R1 submission. Developer tooling — Claude Code GitHub workflow, dependency review, CodeQL, CI-friendly child-process time assertions. Full changelog: https://github.com/ekohan/fleetmix/compare/v1.0.0...v1.1.0