Accessibility: screen containers use a disallowed main role and duplicate the main landmark #526

The wallet's screen containers fail two axe rules. Surfaced while adding the UI Lab accessibility scan (#524); the scan now reports these against the embedded wallet document.

Problem

dockScreen renders each screen as a <main> with an explicit role="tabpanel":

• packages/presentation/wallet-ui/src/sidepanel/shared/parts.ts:450 -> <main class="screen" id="wallet-screen-{view}" role="tabpanel" tabindex="-1">
• packages/presentation/wallet-ui/src/sidepanel/shared/parts.ts:457 -> a second <main class="screen flow" id="wallet-screen-{view}" tabindex="-1">

The review frame that hosts the wallet also has its own <main id="app">, so a docked screen produces:

• aria-allowed-role (minor): ARIA role tabpanel is not allowed for given element on #wallet-screen-home.
• landmark-main-is-top-level (moderate): the main landmark is contained in another landmark (#wallet-screen-send).
• landmark-no-duplicate-main (moderate): more than one main landmark (#app).
• landmark-unique (moderate): landmarks are not distinguishable.

Evidence

axe-core 4.13.0 against the embedded wallet document (UI Lab, Wallet UI Lab / Accessibility scan story), at the 400 x 760 side-panel surface:

• portfolio ready: aria-allowed-role (minor), page-has-heading-one (moderate).
• send review: landmark-main-is-top-level, landmark-no-duplicate-main, landmark-unique (all moderate).

page-has-heading-one is a separate document-level finding and is not part of this report.

Proposed options

Decide the intended semantics before changing markup:

1. Make the hosting <main> the only main, and render docked screens as a non-landmark container (<div> or <section aria-labelledby>), dropping the tabpanel role where the screen is not actually a tab panel.
2. Keep a single main per surface and give each screen a unique accessible name if several remain landmarks.

Either way the fix touches dockScreen and both of its call sites. This report only records the finding; it is not an implementation request.