Because:
- We are updating pairing flows and want to land UI components / pages first.
- Adds the mobile screen confirming the device connected.
This commit:
- Adds `packages/fxa-settings/src/pages/Pair2/Supplicant/SyncSuccess/index.tsx`,
a presentational card rendering the Firefox brand lockup, the shared sync
success illustration, the heading and description copy, a primary "View
synced tabs" button, and a link-styled "Sync settings" button.
- Takes `onViewSyncedTabs` and `onSyncSettings` as required callback props so
that routing the card cannot leave either action inert. Neither action is an
external URL, so no `LinkExternal`; the WebChannel messages, navigation, and
Glean metrics land with the route.
- Adds `en.ftl` with the `pair2-supplicant-sync-success-` strings, a storybook
story, and tests covering the copy, the image aria labels, both callbacks,
and drift between the fallback text and the Fluent bundle.
Closes #FXA-14235