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/battle-viewer-ux.md

@@ -1,7 +1,9 @@
 # Battle Viewer UX
 
-The battle viewer is a dedicated view for battles
-(`/games/<id>/battle/<battleId>`). Bombings are a separate static
+The battle viewer is a dedicated active view for battles
+(`activeView.view === "battle"`, with `battleId` and `turn`
+sub-parameters; the app-shell has no per-view URL — see
+[`navigation.md`](navigation.md)). Bombings are a separate static
 table in the Reports view (`section-bombings.svelte`). The two
 domains are deliberately not mixed in any visual surface or click
 target.
@@ -212,7 +214,8 @@ result is an X-shaped cross overlaid on the planet glyph.
 The stroke width is computed by `battleMarkerStrokeWidth(shots)`:
 1 shot → 1 px, 100 shots → 5 px, linearly interpolated in between
 (`width = 1 + (shots − 1) × 4 / 99`, clamped). A click on either
-line navigates to `/games/<id>/battle/<battleId>?turn=<turn>`.
+line opens the battle viewer in memory via
+`activeView.select("battle", { battleId, turn })`.
 
 ### Bombing marker — colored ring
 
@@ -223,10 +226,10 @@ Colour:
 - yellow (`#FFD400`) when `wiped: false`,
 - red (`#FF3030`) when `wiped: true`.
 
-A click on the ring navigates to `/games/<id>/report#report-bombings`
-and scrolls the matching `report-bombing-row` (by `data-planet`)
-into view. Bombing markers never open the Battle Viewer — the two
-domains stay separate.
+A click on the ring switches to the report view
+(`activeView.select("report")`) and scrolls the matching
+`report-bombing-row` (by `data-planet`) into view. Bombing markers
+never open the Battle Viewer — the two domains stay separate.
 
 ## Data source