chore: upstream dfinity/icp-cli-recipes (prebuilt) moved to prebuilt-v2.1.0

[pr-automation-bot-public]

dfinity/icp-cli-recipes has moved past the ref the docs are verified against.

Pinned in .sources/upstream.json	prebuilt-v2.0.0
Latest release	prebuilt-v2.1.0
Compare	dfinity/icp-cli-recipes@prebuilt-v2.0.0...prebuilt-v2.1.0
Published reference	https://github.com/dfinity/icp-cli-recipes/releases

What to re-check

Cited once, in guides/canister-management/reproducible-builds.md. Each recipe in this repo tags and releases on its own prefix, so it gets its own entry: a single pattern across prefixes would compare rust- against static-site- textually and only ever surface one of them.

How to close this

1. Review the changes above against the pages named under "What to re-check".
2. Update those pages if anything they state has changed.
3. Set pinned to prebuilt-v2.1.0 in .sources/upstream.json in the same PR.

If nothing in the docs is affected, bump the pin on its own and say so in the PR.

Procedure: .agents/upstream-tracking.md

[marc0olo]

Done in #370. Same additive visibility change; the single occurrence of @dfinity/prebuilt@v2.0.0 in guides/canister-management/reproducible-builds.md is now @v2.1.0. Pin moved to prebuilt-v2.1.0.