docs: fix issues with Creating Accounts page (backport #22673)

[AztecBot]

Backport of #22673 to backport-to-v4-next-staging.

The automatic patch-apply backport failed due to two conflicts. Resolved manually following the standard 3-commit backport pattern (without the build-fixes commit — this PR is docs-only and required no code adaptation).

Commits

1. docs: fix issues with Creating Accounts page (backport #22673) — git cherry-pick of upstream squash commit 1c4aa0c. Committed with conflict markers in place so reviewers can see exactly what conflicted.
2. fix: resolve cherry-pick conflicts — minimal edits to the conflicted hunks only.

Conflicts and how they were resolved

Both conflicts boil down to v4-next-staging using different naming than next for things the PR also touched, so a clean three-way merge wasn't possible.

docs/developer_versioned_docs/version-v4.2.0-aztecnr-rc.2/docs/aztec-js/how_to_create_account.md

The original PR edits live under version-v4.2.0/...; on this branch the directory is renamed to version-v4.2.0-aztecnr-rc.2/..., which forced both hunks into a path-rename conflict.

• Install line — kept the 4.2.0-aztecnr-rc.2 version suffix used everywhere else in this file, while still adopting the PR's intended addition of @aztec/noir-contracts.js.
• Sponsored-FPC info note — adopted the PR's reworded sentence ("for more details on the Sponsored FPC and what this snippet means"), but kept the existing #sponsored-fee-payment-contracts anchor since the target heading in this branch's how_to_pay_fees.md is still ### Sponsored Fee Payment Contracts. Switching to #sponsored-fpc would have broken the link on this branch.

docs/docs-developers/docs/aztec-js/how_to_create_account.md

• Sponsored-FPC info note — same wording change as above, but kept the branch's existing anchor #sponsored-fpc-devnet-and-local-only since that branch's how_to_pay_fees.md heading is ### Sponsored FPC (devnet and local only).

Verification

• Cumulative diff stats vs. base match the original PR exactly (3 files, +44 −11).
• No conflict markers remain in any file (grep confirmed).
• docs:start:create_fee_juice_account / docs:end:create_fee_juice_account markers exist in docs/examples/ts/aztecjs_connection/index.ts, so the #include_code reference in the docs-developers file resolves.

Original PR description below for context.

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Summary

Three issues on /developers/docs/aztec-js/how_to_create_account that block users following the guide end-to-end.

1. Install command missing @aztec/noir-contracts.js. The Sponsored FPC snippet imports @aztec/noir-contracts.js/SponsoredFPC, but the Install dependencies section only lists @aztec/aztec.js and @aztec/wallets. Users hit Cannot find module '@aztec/noir-contracts.js/SponsoredFPC'.

2. Misleading info-note wording. Reworded the note below the Sponsored FPC snippet — "setting up" implied the user needed to deploy/configure the canonical contract.

3. Invisible feeJuiceAccount in Verify deployment. The variable was created between docs:start/docs:end markers in the shared example file, so it never made it into the rendered page. Wrapped it in a new docs:start:create_fee_juice_account block; switched verify_account_deployment to reference newAccount with an inline note for the Fee Juice path.

ClaudeBox log: https://claudebox.work/s/ae934d6a0d27b8f5?run=1