Tauri 2.0 platform config merging is shallow, not deep. The Windows
config only specified titleBarStyle, causing minWidth/minHeight to
be missing on Windows. This allowed users to resize the window below
900px, causing header elements to misalign.
The `titleBarStyle: "Overlay"` setting in tauri.conf.json causes black
screen and crash on Windows due to WebView2 compatibility issues.
Add platform-specific config `tauri.windows.conf.json` to override
titleBarStyle to "Visible" on Windows while keeping the overlay style
on macOS for the immersive UI experience.
Fixes black screen issue on Windows for v3.8.x releases.