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/fight_test.go

@@ -7,7 +7,7 @@ import "testing"
 func mkGame(t *testing.T, seed int32) *RogueGame {
 	t.Helper()
 
-	g := NewGame(Config{Seed: seed, Term: &testTerm{}})
+	g := New(Params{Seed: seed, Term: &testTerm{}})
 	g.NewLevel()
 	g.Oldpos = g.Player.Pos
 	g.Oldrp = g.roomIn(g.Player.Pos)