fix(ui): green both lobby scores on a tie, mute a 0:0 board

The lobby tinted only the viewer's own number, and a tie counted as
"leading" — so an even score showed only the viewer's number green,
reading as if the viewer were ahead. A fresh 0:0 board did the same,
accenting the start of a game where nobody has scored.

scoreStanding is now per-seat: the viewer's seat stays green when
leading or tied and red when trailing; an opponent's seat greens only
when it ties the viewer for the lead, so an equal non-zero score paints
both numbers green. When the top score is 0 (nobody has moved) every
number is left muted, like a finished game.

docs/UI_DESIGN.md

@@ -240,8 +240,10 @@ on the right: Victory 🏆 / Defeat 🥈 / Draw 🏅, and for 3–4-player games
 IV 🏅; active games show Your move 🟢 / Opponent's move ⏳; invitations use 💌. The score line
 lists seats in **seat-number order** (matching the over-the-board scoreboard) in a **bold**,
 slightly smaller line; on an **in-progress** game the viewer's **own** number is tinted `--ok`
-when leading or tied and `--danger` when trailing (other numbers stay muted), a quick "am I
-ahead" read that finished games leave to the place emoji. When a listed
+when leading or tied and `--danger` when trailing, and an opponent's number is tinted `--ok` only
+when it **ties the viewer for the lead** (so an equal non-zero score paints both numbers green);
+otherwise numbers stay muted, as does a fresh **0:0** board where nobody has scored yet — a quick
+"am I ahead" read that finished games leave to the place emoji. When a listed
 game **becomes your turn or finishes** while the lobby is open, that status emoji **blinks
 twice** (a two-cycle opacity fade, ~2 s; suppressed under reduce-motion) to draw the eye — the
 opponent's-turn change is silent. Each card's blink is keyed by game id, so overlapping