always draw splitter with accent background color

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: kjk

src/wingui/Splitter.cpp

@@ -197,11 +197,7 @@ LRESULT Splitter::WndProc(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam) {
     }
 
     if (WM_PAINT == msg) {
-        COLORREF col = bgColor;
-        if (isMouseOver) {
-            col = AccentColor(bgColor, 30);
-        }
-        OnSplitterPaint(hwnd, col);
+        OnSplitterPaint(hwnd, AccentColor(bgColor, 30));
         return 0;
     }