test(ui): migrate suite to the app-shell (state-driven navigation)

- Unit: repoint moved screen imports (lib/screens, lib/game), mock
  $lib/app-nav (appScreen/activeView) instead of $app/navigation, drop the
  removed gameId props, assert screen/view selection.
- e2e: add a dev-only window.__galaxyNav affordance; specs enter a game via
  enterGame(...) instead of a /games/:id URL; URL assertions become content
  assertions (the URL stays /game/); reload uses waitUntil:"commit" (shallow
  routing) and mocks /rpc on game entry.
- Remove the obsolete report scroll-restore test (it relied on a SvelteKit
  route Snapshot that no longer exists); update the missing-membership test
  to the new lobby-redirect+toast behaviour. Fix a stale report.svelte
  docstring.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

ui/frontend/src/lib/active-view/report.svelte

@@ -7,15 +7,9 @@ section is its own component under `lib/active-view/report/` — the
 data shapes are too varied for one generic table, and the
 component-per-section seam matches Phase 23's targeted-test contract.
 
-Active-section highlighting and scroll save/restore land here:
-- `IntersectionObserver` rooted on the active-view-host element
-  (`bind:this` in `+layout.svelte`, plumbed through
-  `ACTIVE_VIEW_HOST_CONTEXT_KEY`) watches every `<section
-  id="report-<slug>">` and updates a local `activeSlug` rune.
-- The matching `+page.svelte` exports a SvelteKit `Snapshot` that
-  captures and restores `host.element.scrollTop`, so navigating to
-  /map and back lands on the same scroll position. The save lives in
-  `+page.svelte` because SvelteKit binds snapshots per route.
+Active-section highlighting lands here: an `IntersectionObserver`
+rooted on the viewport watches every `<section id="report-<slug>">`
+and updates a local `activeSlug` rune that drives the TOC highlight.
 
 The 20-section list lives here as a single source of truth so the
 TOC and the body iterate the same data.