Investigations are closed, so strip the probes: bzDbg + __perfProbe definitions, the
older/render/slide/pwaFocus call sites, and the server-side /api/dbg (MDBG) sink. Kept
the functional code around each probe (renderThread's innerHTML build, the older-page
re-anchor, the slide fade). No behavior change. build batch153.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>