Stage 17: bake decisions into PLAN, ARCHITECTURE, FUNCTIONAL(+ru), UI_DESIGN, READMEs; mark stage done

- PLAN: Stage 17 Refinements entry + caveats resolved summary + tracker done
- ARCHITECTURE §7 (move-number robot timing, composed variant-aware names), §10 (move event to the actor too), §11 (game_move_duration metric + offline admin per-user analytics), §14 (current branch model, path-conditional CI + gate, connector liveness)
- FUNCTIONAL(+ru): robot draws language-appropriate names
- UI_DESIGN: screen transitions, Telegram theme/nav, ad-banner accent, players plaque + history drawer
- backend README: robot timing/names refinements

docs/UI_DESIGN.md

@@ -33,6 +33,18 @@ Login uses `Screen`.
   emoji icon over a tiny truncated label. A press highlights a rounded **square** behind
   the icon (slightly larger than it) until release; spacing keeps adjacent labels from
   touching. No text selection on nav / tab-bar / buttons (`user-select: none`).
+- **Screen transitions** (Stage 17, `App.svelte`): navigation slides directionally — a
+  screen entered from the lobby flies in from the right; returning to the lobby reveals it
+  from the left (back). Transitions are local (so they do not play on first load) and
+  collapse to nothing under reduce-motion. A per-game in-memory cache (`lib/gamecache.ts`)
+  renders a re-opened game instantly and refreshes it in the background, removing the
+  blank-loading flash on lobby ↔ game navigation.
+- **Telegram theme** (Stage 17): inside the Mini App the colour scheme is forced from
+  `Telegram.WebApp.colorScheme` (over the OS `prefers-color-scheme`, which leaks into the
+  Telegram Desktop webview and otherwise fights it), the Settings theme switcher is hidden,
+  the nav bar takes Telegram's background (`header_bg_color`), and a live stream dropped by
+  a background suspend silently reconnects on return to the foreground (the connection
+  banner is suppressed while hidden).
 
 ## Tiles & board
 
@@ -45,7 +57,15 @@ Login uses `Screen`.
   they stay a constant size as the cells grow (relatively smaller at higher zoom).
   **Double-tap** toggles zoom and, on touch, placing a tile auto-zooms in centred on the
   target; the custom pinch and swipe-to-open-history gestures were dropped because they
-  fight native scroll — history opens from the menu.
+  fight native scroll — history opens from the menu or a tap on the players plaque (below).
+  A **hint** auto-zooms centred on the hint's placement, not the top-left (Stage 17).
+- **Players plaque & history** (`Game.svelte`, Stage 17): the seats above the board share
+  the width evenly; the seat whose turn it is is **raised** (a drop shadow on its sides)
+  while the others read **sunk in** (an inset shadow). A tap anywhere on the plaque toggles
+  the **move history** — a fixed-height slide-down drawer whose bottom border (and its
+  shadow) pins to the board as the board slides down, instead of tracking the table as
+  moves accumulate; its scrollbar gutter is reserved so the centred word column does not
+  jitter. A move's row lists every word it formed (the main word first).
 - **Highlights**: pending tiles use a slightly darker tile background (no outline). The
   last completed word gets a dark tile background — static while it is the opponent's
   turn (our word), and a 1 s flash when it is our turn (their word). While placing, only
@@ -70,8 +90,10 @@ Login uses `Screen`.
 
 ## Announcement banner (`components/AdBanner.svelte`, `lib/banner.ts`)
 
-A one-line inset strip under the nav bar. Content is minimal markdown (text + links,
-escaped + linkified). A parameterised **rotator** drives messages: a fitting message
+A one-line inset strip under the nav bar, drawn on a dedicated `--ad-bg` token (Stage 17) —
+a subtle accent, a touch darker than the surroundings in the light theme and a touch lighter
+in the dark theme, mapped to Telegram's `secondary_bg_color` inside the Mini App. Content is
+minimal markdown (text + links, escaped + linkified). A parameterised **rotator** drives messages: a fitting message
 holds `holdMs` (default 60 s) then cross-fades to the next; a message wider than the strip
 pauses (`edgePauseMs`), scrolls to its right edge at `scrollPxPerSec`, pauses, and repeats
 until the cycle exceeds `holdMs`. Today a **mock** provider rotates a long and a short