[No QA] [HOLD] Add UK/EU Expensify Card 3DS authentication help article

[MelvinBot]

Explanation of Change

Adds a new New Expensify help article, Approve UK/EU Expensify Card Transactions Using 3DS Authentication, at docs/articles/new-expensify/expensify-card/Approve-UK-EU-Expensify-Card-Transactions-Using-3DS-Authentication.md.

The content is taken from the latest draft in the linked project issue (comment) and covers approving/denying transactions that require 3DS authentication, the ~8-minute approval window, enabling biometric authentication, managing authentication settings, and supported authentication methods.

The article is staged with noindex: true and sitemap: false (and a reminder comment in the YAML header) so it can be merged ahead of go-live without being publicly discoverable, matching the sibling UK/EU Card setup article. Remove those two flags before publishing at launch.

Note: Drafted by MelvinBot at the request of VictoriaExpensify. While transcribing I made these small adjustments — please confirm they're correct:

• Converted the "Screenshot placeholder" note into an HTML TODO comment so it doesn't render on the live page. A real screenshot still needs to be added.
• Fixed a malformed Markdown link in the copilot FAQ answer (the original had stray * characters).
• Possible conflict: there is already a generic Expensify-Card-3D-Secure-Verification.md article that describes a different 3DS flow (SMS one-time passcode entered on the merchant's checkout page, not approved inside Expensify). This new UK/EU article describes in-app biometric/passkey approval. These two articles give contradictory instructions — you may want to scope which card programs each applies to, or consolidate them.

Fixed Issues

$ https://github.com/Expensify/Expensify/issues/503962

Tests

// TODO: The human co-author must fill out the tests you ran before marking this PR as "ready for review"
// Please describe what tests you performed that validates your changed worked.

QA

// TODO: The human co-author must fill out the QA tests you ran before marking this PR as "ready for review".
// Please describe what QA needs to do to validate your changes and what areas do they need to test for regressions.

[OSBotify]

A preview of your ExpensifyHelp changes have been deployed to https://1ff360d7.helpdot.pages.dev ⚡️

Updated articles:

• articles/new-expensify/expensify-card/Approve-UK-EU-Expensify-Card-Transactions-Using-3DS-Authentication

[VictoriaExpensify]

On hold until we go live