[Gusto R2] Surface Gusto on the Members page

[yuwenmemon]

When Gusto is connected, surface the integration on the Members page — show how many members are synced from Gusto, add a manual sync option, and display sync results.

Parent Issues: Expensify/App#85850, Expensify/Expensify#591910
Design Doc Section: Detailed — Release 2: Surface Gusto on the Members page

Files to add/update

• src/pages/workspace/WorkspaceMembersPage.tsx — Add the Gusto subtitle/link, sync spinner, and Sync now menu item.
• src/libs/PolicyUtils.ts — Add a helper that returns how many current members were imported from Gusto.
• src/components/GustoSyncResultsModal.tsx — Reuse the same modal when the Members page is focused and a sync completes.
• src/languages/en.ts — Add members-page-specific strings.

Key implementation details

• If Gusto is connected, add a second line in the Members page header saying how many members are synced from Gusto and link the admin back to HR settings.
• While a Gusto sync is running, show an inline spinner beside that supporting text.
• Add Sync now to the More menu only when Gusto is connected. Call the shared syncConnection(policy, GUSTO) path created in Release 1.
• Reuse the same sync results RHP from the HR page when the Members page is focused and a Gusto sync finishes. If navigated away, do not show it.

Issue Owner

Current Issue Owner: @shubham1206agra

[melvin-bot]

Triggered auto assignment to Design team member for new feature review - @shawnborton (NewFeature)