fix(desktop): keep hit-test fixtures out of foreground

[Astro-Han]

Summary

Refs #1565.

The Astryx hit-test contract needs a compositor-mapped Electron window for elementFromPoint, but it does not need foreground focus. The harness previously set MAKA_E2E_SHOW_WINDOW=1, which routed startup through BrowserWindow.show() and interrupted the developer once per fixture route.

• expose one purpose-specific mapWindowInactive option instead of parallel hidden/inactive/visible mode state
• map the exact Playwright page's BrowserWindow through showInactive(), then fail closed unless it is visible and unfocused
• preserve the existing hidden visual-contract path and Linux CI/Xvfb visible path
• force only inactive Wayland-session launches through XWayland because Electron does not support showInactive() on native Wayland
• cover platform launch arguments, the Playwright-to-Electron boundary, postcondition failure, and hit-test wiring with script tests

Verification

• npm run build — passed
• npm run test:scripts — 224 passed
• npm run lint — passed
• npm run format:check — passed
• npm run typecheck — passed
• npm run check:hit-test — 5/5 routes clean; frontmost-app sampling remained on Ghostty throughout the final run
• npm run check:visual-contract — 20/20 comparisons clean against main; frontmost-app sampling remained on Chrome throughout

Review focus

withFixtureWindow owns the mapping policy: captures stay hidden by default, hit testing requests inactive mapping, and only isolated Linux CI displays use the existing visible startup path. On a Wayland session, the inactive launch adds --ozone-platform=x11; all other launch modes retain Electron's platform default.