[client] overlay: restore every splash fade frame

Mark the active fade as requiring a fully restored render target.
This also covers guest-driven renders between animation ticks so they
cannot blend over stale splash content.

client/src/app.c

@@ -1030,6 +1030,27 @@ bool app_overlayNeedsRender(void)
   return result;
 }
 
+bool app_overlayNeedsFullRender(void)
+{
+  bool result = false;
+  struct Overlay * overlay;
+  ll_lock(g_state.overlays);
+  ll_forEachNL(g_state.overlays, item, overlay)
+  {
+    if (!overlay->ops->needs_full_render)
+      continue;
+
+    if (overlay->ops->needs_full_render(overlay->udata))
+    {
+      result = true;
+      break;
+    }
+  }
+  ll_unlock(g_state.overlays);
+
+  return result;
+}
+
 int app_renderOverlay(struct Rect * rects, int maxRects)
 {
   int  totalRects  = 0;

client/src/main.c

@@ -695,7 +695,9 @@ static int renderThread(void * unused)
       atomic_compare_exchange_weak(&g_state.lgrResize, &resize, 0);
     }
 
-    const bool invalidate = atomic_exchange(&g_state.invalidateWindow, false);
+    const bool invalidate =
+      atomic_exchange(&g_state.invalidateWindow, false) ||
+      app_overlayNeedsFullRender();
 
     const LG_RendererFrameToken frameTokenLimit = frameTimingQueuedToken();
     const uint64_t              prepareStart    = nanotime();

client/src/overlay/splash.c

@@ -247,13 +247,19 @@ static bool splash_tick(void * udata, unsigned long long tickCount)
   return false;
 }
 
+static bool splash_needsFullRender(void * udata)
+{
+  return !l_show && !l_fadeDone;
+}
+
 struct LG_OverlayOps LGOverlaySplash =
 {
-  .name   = "splash",
-  .init   = splash_init,
-  .free   = splash_free,
-  .render = splash_render,
-  .tick   = splash_tick,
+  .name              = "splash",
+  .init              = splash_init,
+  .free              = splash_free,
+  .needs_full_render = splash_needsFullRender,
+  .render            = splash_render,
+  .tick              = splash_tick,
 };
 
 void overlaySplash_show(bool show)