Docs updates for E/A#93063 Add currency selection to card rules

[MelvinBot]

Why this PR

This updates the help site to match the changes from #93063, which restructured the Expensify Card Spend rules UI:

• Restriction type (Allow / Block) is replaced by Restrict merchants with three options: Off, Allow, and Block.
• A new Permitted currencies setting was added (default All currencies, with the option to select specific currencies). The card's settlement currency is always permitted, and selecting specific currencies (or a max amount) requires the selected cards to settle in the same currency.
• Spend category is now surfaced as merchant types — Allowed merchant types / Blocked merchant types — alongside Allowed merchants / Blocked merchants.
• The section is now titled Spend rules, and the save action is Save rule.

What changed

Updated docs/articles/new-expensify/expensify-card/Expensify-Card-Spend-Rules.md:

• Reworked the configuration section into What you can configure in an Expensify Card Spend rule, documenting Permitted currencies, Max amount, and the Restrict merchants Off/Allow/Block options.
• Updated the create, edit/delete, and issue-a-card steps to match the new UI and exact labels (Choose cards, Add spend rule, Save rule, Delete rule).
• Updated the intro, metadata (description/keywords/internalScope), and FAQ (added a same-settlement-currency FAQ; removed the outdated "uses either Allow or Block" wording).

All UI labels were taken verbatim from src/languages/en.ts in the linked PR.

Source

Help site changes for #93063.

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@JS00001, please review the files changed and confirm they reflect the current behavior. Then mark this PR Ready for review.