docs: document initializerless accounts (v5-next backport of #24512)

[AztecBot]

Backport of #24512 ("docs: document initializerless accounts") into v5-next, requested by Alejo in Slack.

What this adds (same as the original PR)

• New concept page foundational-topics/accounts/deployment.md ("Account Deployment"): the standard initialize-and-deploy flow vs the initializerless flow, how the signing key is committed into the address via immutables_hash, and the trade-offs (no deploy cost/delay; signing key fixed forever; per-PXE local setup; getDeployMethod() throws).
• New "Create an initializerless account" section in aztec-js/how_to_create_account.md with the createSchnorrInitializerlessAccount snippet and caveats.
• Cross-links from fees.md, wallets.md, contract_creation.md, and aztec-nr/framework-description/immutables.md.

How the backport differs from the original

• The original PR mirrored all changes into developer_versioned_docs/version-v5.0.0-rc.2/. That snapshot does not exist on v5-next (the only snapshot here is version-v4.3.0, which documents the v4 line and must not describe a v5-only feature), so this backport touches only the current docs under docs/docs-developers/. Git's directory-rename detection tried to remap the mirrored copies into the v4.3.0 snapshot during the cherry-pick; those were dropped deliberately.
• Everything else is the original commit cherry-picked verbatim; the only diff-vs-original differences are context lines where v5-next prose already diverged from next.

Notes

• Unlike next, createSchnorrInitializerlessAccount does exist in this branch's yarn-project (verified), so the fenced snippet could be converted to an #include_code example here as a follow-up. Kept as a fenced block for a faithful backport.
• Verified all new internal links resolve to files present on v5-next, and initializerless is already in docs-words.txt on this branch.

Refs #24512.

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Created by claudebox · group: slackbot