✨ Add "experimental" entry point for new APIs

[cowboyd]

Motivation

We've been staging new API surface (context APIs, inspectable attributes, api() decorator machinery) on the v4-1-alpha branch behind an ./experimental export. Rather than land that alpha branch as a single mega-merge, we're peeling it apart into feature PRs against v4.

This first PR is the foundation: it wires up the ./experimental entry point so subsequent PRs (context APIs, etc.) have somewhere to land without touching the stable mod.ts surface.

Approach

• deno.json — split exports into . (mod) and ./experimental (experimental); include experimental.ts in publish set.
• experimental.ts — empty for now; content lands with follow-up PRs.

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/effection@1210

commit: c6d56a4

[codspeed-hq]

Merging this PR will not alter performance

✅ 6 untouched benchmarks

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_{Comparing v4-experimental-infra (c6d56a4) with v4 (c4d14f6)}