docs(ui): sync docs to the app-shell; fix stale nav comments

Rewrite ui/docs (navigation, order-composer, auth-flow, pwa-strategy,
game-state + secondary topic docs) and ui/README for the single-URL
app-shell (in-memory screens/views, Back→lobby via shallow routing,
sessionStorage restore + validation, return-to-lobby). ui/PLAN.md gets a
Phase-10 supersede note (implemented; standalone-compatible). Fix stale
code comments (session-store auth gate, report-sections spec contract).

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

ui/docs/order-composer.md

@@ -195,15 +195,15 @@ Lifecycle:
 | `dispose()`                          | Marks the store destroyed; subsequent `persist()` calls are no-ops so a fast game-switch does not write stale state into the next id. |
 
 Mutations made before `init` resolves are silently ignored — the
-layout always awaits `init` through `Promise.all([...])` next to
+shell always awaits `init` through `Promise.all([...])` next to
 `gameState.init` before exposing the store.
 
-Layout integration mirrors `GameStateStore`:
+Shell integration mirrors `GameStateStore`:
 
-- One instance per game, created in
-  [`../frontend/src/routes/games/[id]/+layout.svelte`](../frontend/src/routes/games/[id]/+layout.svelte).
+- One instance per game, created in the in-game shell
+  [`../frontend/src/lib/game/game-shell.svelte`](../frontend/src/lib/game/game-shell.svelte).
 - Exposed through the `ORDER_DRAFT_CONTEXT_KEY` Svelte context.
-- Disposed in the layout's `onDestroy`.
+- Disposed in the shell's `onDestroy`.
 
 The order tab and the planet inspector both consume the store via
 `getContext(ORDER_DRAFT_CONTEXT_KEY)` to push new commands.
@@ -257,7 +257,7 @@ snapshot (history mode is the planned reader).
 
 `OrderDraftStore` records `needsServerHydration = true` when no
 cache row exists for the active game (fresh install, cleared
-storage, switching device). After the layout boot resolves both
+storage, switching device). After the shell boot resolves both
 `gameState.init` and `orderDraft.init`, it calls
 `orderDraft.hydrateFromServer({ client, turn })` which issues
 `user.games.order.get` against the gateway. A `found = false`
@@ -294,14 +294,12 @@ report as it was. The Order tab is hidden when history mode is active
 — the player is browsing an immutable snapshot, and composing commands
 against it would be confusing.
 
-The layout owns the `historyMode` flag and passes it to:
+The in-game shell owns the `historyMode` flag and passes it to:
 
 - `Sidebar` as `historyMode`. The sidebar forwards it to its
   `TabBar` as `hideOrder`. The Order entry is filtered out of the
-  tab list when true. If a `?sidebar=order` URL seed lands while
-  the flag is true, the sidebar falls back to `inspector`. If the
-  active tab is `order` when the flag flips on, an effect resets
-  it to `inspector`.
+  tab list when true. If the active tab is `order` when the flag
+  flips on, an effect resets it to `inspector`.
 - `BottomTabs` as `hideOrder`. The mobile bottom-tab `Order`
   button is suppressed when true.