Stage 17: UI defect fixes (russian variant, Telegram theme/nav/banner, reconnect, hint zoom, plaque, history, transitions, per-game cache)

- #6 align the UI variant id to the backend canonical 'russian_scrabble' (type, variants, Lobby, mock, tests) — fixes the New->Russian 400
- #11/#12 inside Telegram force the colour scheme from WebApp.colorScheme (over OS prefers-color-scheme, fixing the Telegram Desktop breakage) and hide the theme switcher
- #14/#15 nav bar takes Telegram's bg; announcement banner gets a dedicated subtle --ad-bg accent token
- #16 suppress the reconnect banner while backgrounded and silently reconnect the live stream on return to the foreground
- #17 hint zoom scrolls to the placement's bounding box, not the top-left
- #19/#20 players plaque: active seat raised with side shadows, others sunk; tap toggles history
- #21/#23 history: scrollbar-gutter:stable (no word jitter); fixed-height drawer pins the bottom shadow to the board
- #3 (UI) disable nudge on the player's own turn
- #18a directional screen slide transitions (forward in from the right, back reveals the lobby)
- #13 per-game in-memory cache: instant render on re-entry + background refresh
- e2e: openGame waits for the slide transition to settle

ui/src/lib/mock/alphabet.ts

@@ -12,7 +12,7 @@ import type { Variant } from '../model';
 const SPECS: Record<Variant, string> = {
   english:
     'a1 b3 c3 d2 e1 f4 g2 h4 i1 j8 k5 l1 m3 n1 o1 p3 q10 r1 s1 t1 u1 v4 w4 x8 y4 z10',
-  russian:
+  russian_scrabble:
     'а1 б3 в1 г3 д2 е1 ё3 ж5 з5 и1 й4 к2 л2 м2 н1 о1 п2 р1 с1 т1 у2 ф10 х5 ц5 ч5 ш8 щ10 ъ10 ы4 ь3 э8 ю8 я3',
   erudit:
     'а1 б3 в2 г3 д2 е1 ё0 ж5 з5 и1 й2 к2 л2 м2 н1 о1 п2 р2 с2 т2 у3 ф10 х5 ц10 ч5 ш10 щ10 ъ10 ы5 ь5 э10 ю10 я3',

ui/src/lib/mock/client.ts

@@ -62,7 +62,7 @@ function emptyLinked(): LinkResult {
 
 const POOL: Record<Variant, string> = {
   english: 'AAAAEEEEIIIOONNRRTTLLSSUDGBCMPFHVWYK',
-  russian: 'ОООААЕЕИИННТТСРРВЛКМДПУЯЫЬГЗБ',
+  russian_scrabble: 'ОООААЕЕИИННТТСРРВЛКМДПУЯЫЬГЗБ',
   erudit: 'ОООААЕЕИИННТТСРРВЛКМДПУЯЫЬГЗБ',
 };
 

ui/src/lib/mock/data.ts

@@ -203,7 +203,7 @@ function finishedG3(): MockGame {
   return {
     view: {
       id: 'g3',
-      variant: 'russian',
+      variant: 'russian_scrabble',
       dictVersion: 'v1',
       status: 'finished',
       players: 2,