result: play the cover back for a retry

The engine's retry flow calls ResultFadeIn:start_reverse; this override
of the parent's result_fade_in.lua had no such method, so the result
background never closed back over the screen before the retry.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Scripts/result/result_fade_in.lua

@@ -22,6 +22,12 @@ function ResultFadeIn.new(player_num)
     return self
 end
 
+-- retry: the parent plays the same cover back the other way, closing over the screen
+function ResultFadeIn:start_reverse()
+    self.reversed = true
+    self.fade_in:restart()
+end
+
 function ResultFadeIn:update(current_ms)
     self.fade_in:update(current_ms)
 end
@@ -31,9 +37,11 @@ function ResultFadeIn:is_finished()
 end
 
 function ResultFadeIn:draw()
+    local fade = self.fade_in.attribute
+    if self.reversed then fade = 1 - fade end
     if self.layers then
-        self.layers:draw(self.fade_in.attribute, __hss_result_bg_clear or 0.0)
+        self.layers:draw(fade, __hss_result_bg_clear or 0.0)
     elseif self.t_bg then
-        tex.draw_texture(self.t_bg, { fade = self.fade_in.attribute })
+        tex.draw_texture(self.t_bg, { fade = fade })
     end
 end