v0.4.0

v0.4.0 — drift detection, observability, and hot reload

bundle draft-shim auto-drafts a transform-shim override from two layers'
OpenAPI documents: confident stanzas for unambiguous changes, candidates
blocks for ambiguous renames the operator must resolve before bundle
verify accepts the result. Per-request structured logging and labelled
metrics (contract_version, transform_outcome) let an operator slice
traffic and failures by cohort. SIGHUP swaps the bundle in place;
buf breaking gates wavefront.v0.Error against breaking edits.