fix(ui): one-word games must not highlight phantom cross words; review polish

Board-highlight bug (reported on the contour): formedGeometry walked cross words
unconditionally, so in a single-word (one-word-per-turn) game a staged tile sitting
next to a committed tile lit up a green "cross word" the engine ignores — and which
need not even be a real word (the reported "БО lights up green in a one-word ПОПА
play"). Gate the cross-word walk on the game's multipleWordsPerTurn flag. The score
(8) was already correct — a premium square under the main word.

Also, from review:
- the turn strip reads the staged play's "WORD+WORD = N" while composing a legal move,
  reverting to the turn / result text otherwise;
- the Exchange/Pass dialog shows the bag count ("In the bag: N" / "Bag is empty")
  right-aligned in the title row, via a new optional Modal `titleAside`;
- cosmetics: half the turn strip's bottom padding (the plaques below carry their own
  top pad); a top gap above the landscape rack (it sat flush under the docked history);
  more horizontal padding on tab count badges so a 2-3 digit bag count clears the pill
  ends;
- admin console: the game Summary now shows the single-word / multiple-words rule.

Tests: formed single-word case added; full unit (584) + e2e (chromium + webkit, 113
each) green; backend build + adminconsole templates parse. Docs (FUNCTIONAL +_ru,
UI_DESIGN) updated.

docs/UI_DESIGN.md

@@ -249,7 +249,8 @@ e2e and the screenshots.
   width in both layouts, so the tiles are square and as large as the row allows (the confirm ✅ takes
   the fixed 7th slot while a play is staged).
 - **Highlights**: while composing a play the staged tiles are **tinted by legality** — a light
-  green once they form a word (a shade darker on the committed board tiles the word runs through),
+  green once they form a word (a shade darker on the committed board tiles the word runs through —
+  in a **single-word game** only the main word lights up, since the engine ignores cross words),
   a calm pink when they form none — and an **orange score badge** sits on a corner of the main
   word's tile, its digit sized like a tile's point value (so it scales with the zoom) and clamped
   to stay on the board. Off-turn or with no preview the staged tiles keep the plain pending fill.
@@ -286,9 +287,10 @@ e2e and the screenshots.
   remains), 🛟 Hint (with a remaining-count badge, disabled at zero); 🔀 Shuffle (no label,
   no confirm), which
   **animates** — tiles hop along a low parabola to their new slots (duration scaled by the
-  distance, the longest ≤ 0.3 s; off under reduce-motion) with a short haptic shake. Whose turn it
-  is — or the viewer's result once the game ends — shows in a **thin strip above the score
-  plaques**; the tentative move's score rides the board badge (above), not an under-board caption.
+  distance, the longest ≤ 0.3 s; off under reduce-motion) with a short haptic shake. A **thin strip
+  above the score plaques** reads, while composing a legal play, the formed word(s) and the move
+  score ("WORD+WORD = N"); otherwise whose turn it is, or the viewer's result once the game ends. The
+  move score also rides the board badge (above), never an under-board caption.
   The screen **title** is the variant's
   display name (Scrabble / Скрэббл / Erudite / Эрудит), not a constant "Scrabble".