Add boss team match playstyle rule

When enabled, the sticky boss banner shows the next boss's team size
as a hint for players who voluntarily match the boss's party count.
Handles variant boss teams by using the auto-detected starter variant.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/pages/RunEncounters.tsx

@@ -178,6 +178,17 @@ function matchVariant(labels: string[], starterName?: string | null): string | n
   return matches.length === 1 ? (matches[0] ?? null) : null
 }
 
+/** Count boss pokemon for the effective variant (or all if no variants). */
+function getBossTeamSize(pokemon: BossPokemon[], starterName?: string | null): number {
+  const labels = [
+    ...new Set(pokemon.filter((bp) => bp.conditionLabel).map((bp) => bp.conditionLabel!)),
+  ]
+  if (labels.length === 0) return pokemon.length
+  const matched = matchVariant(labels, starterName)
+  const variant = matched ?? labels[0] ?? null
+  return pokemon.filter((bp) => bp.conditionLabel === variant || bp.conditionLabel === null).length
+}
+
 function BossTeamPreview({
   pokemon,
   starterName,
@@ -1060,7 +1071,15 @@ export function RunEncounters() {
                 Level Cap: {currentLevelCap ?? '—'}
               </span>
               {nextBoss && (
-                <span className="text-sm text-text-tertiary">Next: {nextBoss.name}</span>
+                <span className="text-sm text-text-tertiary">
+                  Next: {nextBoss.name}
+                  {run.rules?.bossTeamMatch && (
+                    <span className="text-text-muted">
+                      {' '}
+                      ({getBossTeamSize(nextBoss.pokemon, starterName)} Pokémon — match their team)
+                    </span>
+                  )}
+                </span>
               )}
               {!nextBoss && (
                 <span className="text-sm text-status-active">All bosses defeated!</span>