Drop the progressive benchmark, remove dead wrap scaffolding

Review fallout from removing progressive publication.

The Live benchmark existed to compare atomic against progressive delivery:
compareModelBackedReports measures goToFirstVariantMs improvement of one
over the other. With progressive gone it measures nothing against nothing.
Worse, benchmark-live.mjs still passed `progressive` to bootFixtureSession,
which no longer accepts it, so `--delivery progressive` was silently
ignored and would have emitted reports labeled progressive that actually
ran atomic. Silent wrong data is worse than a crash. It was built for
progressive, so it goes with progressive: benchmark-live.mjs, its lib, its
test, and the bench:live script. If an atomic latency baseline is wanted
later, that is a smaller thing built on purpose.

live-wrap.mjs: sourceOriginalLines was assigned and never read.

Both found by review bots on #381 (Copilot).

Assisted-by: Claude Code

package.json

@@ -68,7 +68,6 @@
     "smoke:hooks": "node scripts/smoke-provider-hooks.mjs",
     "bench:detector": "node scripts/benchmark-detector.mjs",
     "bench:detector:browser": "node scripts/benchmark-detector.mjs --browser",
-    "bench:live": "node scripts/benchmark-live.mjs",
     "audit": "bun audit --audit-level=moderate",
     "prepack": "cp README.md README.repo.md && cp README.npm.md README.md",
     "postpack": "cp README.repo.md README.md && rm README.repo.md",