Two builds of the same source tree could publish different artifacts
because buildEmbeddedPatterns.ts and buildTypeEmbeddings.ts stamped
their generated output with new Date().toISOString(). Route both
generators' "Generated:" header and the generatedAt runtime field
through a shared resolver: newest git commit time among the
generator's inputs (script + source data), falling back to the stamp
already present in the previous output when git is unavailable (e.g.
a published tarball build), and finally to a fixed epoch value. Every
fallback logs to stderr so degradation is never silent.
Regenerated both committed output files once so the tree carries
deterministic stamps; no other content changed.
