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/tables_test.go

@@ -32,7 +32,7 @@ func TestProbabilitiesSumTo100(t *testing.T) {
 }
 
 func TestInitProbsCumulative(t *testing.T) {
-	g := NewGame(Config{Seed: 1})
+	g := New(Params{Seed: 1})
 
 	last := g.Items.Potions[NumPotionTypes-1].Prob
 	if last != 100 {
@@ -47,14 +47,14 @@ func TestInitProbsCumulative(t *testing.T) {
 }
 
 func TestNewGameRandomizesAppearances(t *testing.T) {
-	g := NewGame(Config{Seed: 12345})
+	g := New(Params{Seed: 12345})
 
 	checkPotionColors(t, g)
 	checkScrollNames(t, g)
 	checkWandMaterials(t, g)
 
 	// Determinism: same seed, same appearances.
-	h := NewGame(Config{Seed: 12345})
+	h := New(Params{Seed: 12345})
 	if h.Items != g.Items {
 		t.Error("two games with the same seed produced different item lore")
 	}