Rename constructor to game.New(game.Params) per styleguide

NewGame(Config) becomes New(Params), and Restore takes Params too, so
the package's primary type gets the canonical New() constructor with a
named-field Params struct (styleguide points 139, 159). cmd/rogue and
all tests updated; ARCHITECTURE.md constructor references corrected.
Pure rename, suite green.

game/newlevel_test.go

@@ -8,7 +8,7 @@ import (
 func genLevel(t *testing.T, seed int32) *RogueGame {
 	t.Helper()
 
-	g := NewGame(Config{Seed: seed})
+	g := New(Params{Seed: seed})
 	g.NewLevel()
 
 	return g
@@ -159,7 +159,7 @@ func TestNewLevelDeterministic(t *testing.T) {
 // mazes, dark rooms, traps, treasure rooms — as a crash/invariant sweep.
 func TestDeeperLevels(t *testing.T) {
 	for _, seed := range []int32{7, 42, 1000, 31337} {
-		g := NewGame(Config{Seed: seed})
+		g := New(Params{Seed: seed})
 		for depth := 1; depth <= 30; depth++ {
 			g.Depth = depth
 			g.NewLevel()