widescreen: cinematic letterbox bars span the render width

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

src/mods/widescreen.cpp

@@ -236,6 +236,16 @@ void PatchLabelArea(int width, int height) {
             static_cast<int>(std::size(game::addr::kLabelAreaPushes)) * 2);
 }
 
+// Cinematic bars span the screen width.
+void PatchLetterbox(int width) {
+    int patched = 0;
+    for (uint32_t site : game::addr::kLetterboxRightImmediates) {
+        patched += re::PatchInstructionDword(site, FloatBits(1024.0f), FloatBits(static_cast<float>(width)));
+    }
+    re::Log("widescreen: %d/%d letterbox immediates patched", patched,
+            static_cast<int>(std::size(game::addr::kLetterboxRightImmediates)));
+}
+
 } // namespace
 
 void ApplyRenderSize(game::DxDisplayMode& mode, HWND window) {
@@ -287,6 +297,7 @@ void ApplyRenderSize(game::DxDisplayMode& mode, HWND window) {
         PatchCenterImmediates(width, height);
         PatchGrannyOrthoPushes(width, height);
         PatchLabelArea(width, height);
+        PatchLetterbox(width);
     }
     const double scaleX = width / kOriginalWidth;
     const double scaleY = height / kOriginalHeight;