test(perf): count update cycles, model builds and adoptions during boot (#520)

The full comparison says model readiness grew by ~500 ms inside #500 and
that the growth sits in one long task, but neither contentFingerprint
(2.8 ms on this fixture) nor spaceModels (0.1 ms) can account for it. The
benchmark now prints, per sample, how many Lit update cycles ran before the
first stable frame, how long they took together, how many models were built,
how many adoptions happened and the config epoch. Diagnostics only: printed
to the log, never part of the budgeted record, and the same harness runs
against the comparison bundle, so candidate and base are counted alike.

Issue: #520
User-Visible: no

node_modules

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