ADR 0007 proof of concept

Experiments backing doc/ai/adr/0007-deferred-core-fn-costs.md.

Mechanism POCs (standalone node, self-contained):

• perf.cjs - hot-path perf of the dispatch mechanisms (node perf.cjs, or EXTENDED=1 node perf.cjs). Shows the registry hybrid is perf-neutral and wrapping regresses once an extend-type exists.
• dce.cjs - a toy model of whether a protocol-free base lets slot symbols shake out (node dce.cjs; needs esbuild). NOTE: this only models the symbols, not the dispatch-branch code, so it over-states the win - the real measurement below corrects it.
• extend.cjs - whether a user can still extend a built-in protocol in the registry model (node extend.cjs).

Real measurement (the one that decided it): transform the shipping 0.14.206 core.js in place, hold the reagami app/lib constant, rebuild, compare gzip.

• measure-ceiling.cjs - rewrites every protocol-slot access to (void 0) so esbuild folds the dispatch branches away AND drops the now-unused symbols. Produces the ceiling core (all slot dispatch gone).
• measure-registry.cjs - collapses the 34 slot symbols to one, keeping the dispatch branches - i.e. what a registry actually recovers (symbols only).

Result on the reagami js-framework-benchmark app (gzip):

variant	gzip	recovers
baseline (as ships)	9201	-
registry (symbols gone, branches kept)	8894	307 B
ceiling (all slot dispatch gone)	8301	900 B

Conclusion: a registry recovers ~307 bytes, the ceiling 900; not the ~1.5 KB the version-to-version delta suggested. Keep the baseline.