Let players peek both decks during and after a battle

Record each seat's arranged lineup on the battle result (already public)
and reveal the full deck in a popover when hovering a deck pile in the
battle view — the opponent's included.

internal/game/battle.go

@@ -102,12 +102,14 @@ type BattleEvent struct {
 	Bonus int `json:"bonus"`
 }
 
-// BattleResult is the full, public record of one round's battle. Only what
-// was revealed appears in Events; the rest of the winner's stack stays
-// hidden.
+// BattleResult is the full, public record of one round's battle.
 type BattleResult struct {
-	Round      int           `json:"round"`
-	StackSizes []int         `json:"stackSizes"` // starting deck size per seat
+	Round      int   `json:"round"`
+	StackSizes []int `json:"stackSizes"` // starting deck size per seat
+	// Lineups is each seat's arranged deck at battle start (top of deck
+	// first). Public so players can review the whole matchup — including the
+	// opponent's cards — during and after the fight.
+	Lineups    [][]Card      `json:"lineups,omitempty"`
 	Events     []BattleEvent `json:"events"`
 	WinnerSeat int           `json:"winnerSeat"` // -1 = draw
 	Trophies   int           `json:"trophies"`   // awarded to the winner
@@ -189,7 +191,7 @@ func effectCount(e Effect, s *battleSide, u *BattleUnit) int {
 // stalemate.
 func (g *Game) resolveBattle() {
 	n := len(g.Players)
-	res := &BattleResult{Round: g.Round, WinnerSeat: -1, StackSizes: make([]int, n)}
+	res := &BattleResult{Round: g.Round, WinnerSeat: -1, StackSizes: make([]int, n), Lineups: make([][]Card, n)}
 	sides := make([]*battleSide, n)
 	emit := func(ev BattleEvent) { res.Events = append(res.Events, ev) }
 
@@ -197,6 +199,7 @@ func (g *Game) resolveBattle() {
 		s := &battleSide{stack: append([]Card(nil), p.Deck...)}
 		sides[p.Seat] = s
 		res.StackSizes[p.Seat] = len(p.Deck)
+		res.Lineups[p.Seat] = append([]Card(nil), p.Deck...)
 	}
 	// seatOrder resolves the priority-token holder first, then everyone else.
 	// Reveals, queued play effects, and cross-side triggers all follow it, so