games: UNO becomes a table you sit at, and the pot that pays whoever goes out first

Phase D backend: UNO is now a session like hold'em, not a single stake. You sit
with a buy-in stack, ante into a pot each hand, and leave with what's in front of
you. The engine lost its `You` constant and its measured multiples: ApplyMove
takes the acting seat, New takes a seat list, a Tier carries an ante instead of a
Base, and a hand settles by moving the pot to the winner (less rake, and never
when a bot takes it) rather than paying a multiple. A mercy kill puts a seat out
of the hand, not out of the game — the last one standing takes the pot.

The redaction moved to the web layer, where hold'em's already lives: the engine
now stamps every seat's hand onto its events, and viewUno/viewUnoEvents strip
everything that isn't the viewer's own. TestUnoViewNeverLeaksAnotherSeatsCards is
the wall. unoTable implements tableGame; /uno/{sit,move,leave,tables,stream,chat,
say} mirror hold'em, with stream/chat/say now shared game-agnostic handlers.

The frontend is not done: uno.js still calls the retired solo endpoint, so the
page renders but is not yet playable. All engine and web tests are green.

Claude-Session: https://claude.ai/code/session_013M5nD7PgUboJXoDcYHzpuJ

internal/web/templates/uno.html

@@ -174,11 +174,11 @@
                 class="pete-tier rounded-2xl border-2 p-3 text-left transition">
           <div class="flex items-baseline justify-between gap-2">
             <span class="font-display text-lg font-bold">{{.Name}}</span>
-            <span class="font-display text-lg font-bold tabular-nums text-[color:var(--accent)]">{{printf "%.1f" .Base}}×</span>
+            <span class="font-display text-lg font-bold tabular-nums text-[color:var(--accent)]">{{.Ante}} ante</span>
           </div>
           <p class="mt-0.5 text-xs text-[color:var(--ink)]/50">{{.Blurb}}</p>
           <p class="mt-1.5 text-xs font-semibold text-[color:var(--ink)]/40">
-            {{.Bots}} bot{{if gt .Bots 1}}s{{end}} · seven cards each
+            {{.Bots}} bot{{if gt .Bots 1}}s{{end}} · winner takes the pot
           </p>
         </button>
         {{end}}
@@ -192,7 +192,7 @@
                 class="pete-tier pete-tier-nm rounded-2xl border-2 p-3 text-left transition">
           <div class="flex items-baseline justify-between gap-2">
             <span class="font-display text-lg font-bold">{{.Name}}</span>
-            <span class="font-display text-lg font-bold tabular-nums text-[color:var(--accent)]">{{printf "%.1f" .Base}}×</span>
+            <span class="font-display text-lg font-bold tabular-nums text-[color:var(--accent)]">{{.Ante}} ante</span>
           </div>
           <p class="mt-0.5 text-xs text-[color:var(--ink)]/50">{{.Blurb}}</p>
           <p class="mt-1.5 text-xs font-semibold text-[color:var(--ink)]/40">