v0.7.1

v0.7.1

Release scope:

• Patch release for the HigherGraphen Rust workspace at 0.7.1.
• Three general-purpose primitive improvements over the v0.7.0 advisory
  extensions, requested by AdvisoryGraphen. All additive and deterministic, no
  new dependencies, no consumer domain vocabulary. Design spec:
  docs/specs/incidence-evaluator-hardening.md.
• Git tag and GitHub Release are prepared for publication after maintainer
  approval.

Highlights:

• Incidence severity (latent-gap fix): reasoning::incidence obstructions no
  longer hardcode Severity::Medium. IncidenceRelation::with_dangling_severity
  / with_context_mismatch_severity and RequiredRegion::with_severity let the
  caller declare a finding's severity. Default stays Medium.
• Acyclicity parity: EvaluatorCheck::Acyclicity now reports every simple cycle
  with edge witnesses (related_morphism_ids) and a per-cycle counterexample,
  backed by the existing InMemorySpaceStore::find_simple_cycles (the bespoke
  single-cycle DFS is removed). The reported representation changed from the
  single-cycle message to an all-cycles, witnessed form.
• Cross-context policy: IncidenceRelation::with_cross_context_allowed()
  suppresses the context-mismatch obstruction for legitimately cross-context
  edges; default unchanged.