fix: center header content with symmetric padding

Use pt-3 pb-3 (12px each) for symmetric vertical padding so content
is visually centered in every header bar.

To keep headers draggable, each header container gets the drag-region
class and all interactive elements (buttons) get the no-drag class.
The global fallback drag strip is reduced to h-3.
Title bar overlay reduced from 40px to 32px (standard Windows size).

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/main/windows/createMainWindow.ts

@@ -21,7 +21,7 @@ export function createMainWindow(): BrowserWindow {
     titleBarOverlay: {
       color: '#09090b',
       symbolColor: '#a1a1aa',
-      height: 40,
+      height: 32,
     },
     webPreferences: {
       preload: join(__dirname, '../preload/index.js'),