Docs updates for E/A#92787 Authorized payer for manual reimbursement

[MelvinBot]

Explanation of Change

Follow-up documentation for Expensify/App#92787, which allows manual/indirect payment (reimburseManual, "Mark as Paid") workspaces to set and use a preferred payer — the same way direct payment workspaces already could.

Previously the Payer field on the Workflows tab only appeared when a bank account was connected. Now a Workspace Admin can designate an Authorized payer even without a connected bank account, and only that payer is prompted to pay reports.

What changed in the docs

Updated docs/articles/new-expensify/workspaces/Workspace-Workflows.md:

• Added How to choose an authorized payer without a connected bank account documenting that the Payer field is now available when Payments is enabled, even with no bank account.
• Added What happens after you set an authorized payer explaining that only the authorized payer is prompted to pay (payment reminder in the Inbox and a Pay button next to the workspace chat), while other admins can still pay a report but aren't prompted.
• Added authorized payer, mark as paid, and payer keywords for retrieval.

All UI labels (Payments, Payer, Authorized payer, Pay, Workspaces, Workflows) were verified against the current App UI and language files, and the changes follow HELPSITE_NAMING_CONVENTIONS.md, HELP_AUTHORING_GUIDELINES.md, and TEMPLATE.md (task-based ## headings, exact UI casing, non-rendered screenshot placeholder).

Related

• Source PR: [Payment due @dmkt9] Allow manual reimbursement workspaces to set and use a preferred payer #92787
• Parent issue: https://github.com/Expensify/Expensify/issues/637864

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@NikkiWines, please review the files changed and confirm they reflect the current behavior. Then mark this PR Ready for review.