fix: approval windows open as wide as the page (closes #518)

The approval window was opened 360 pixels wide while the page is 396, so
it scrolled sideways and cut off the Reject button. It now opens at 396.
Both browsers count the window's frame in that width, so the approval
page also widens its own window by however far it would scroll sideways;
the toolbar popup's window is left alone. The Firefox suite checks that
the sign prompt does not scroll sideways. The Chrome suite cannot: its
approval windows open at 1280x720 whatever size is asked. README's Visual
Style line, which still said 360x600, now gives the page's real width.

Model: opus-5-5

tests/e2e/firefox/run.js

@@ -640,6 +640,19 @@ step(
         await d.switchToWindow(popup);
         await d.waitVisible("#view-approve-sign");
 
+        // The window is opened as wide as the page
+        // (https://git.eeqj.de/sneak/AutistMask/issues/518). This suite is
+        // where that is checked: the Chrome suite's approval windows open at
+        // 1280x720 whatever width the extension asks for.
+        const sideways = await d.execute(
+            "return document.documentElement.scrollWidth -" +
+                " document.documentElement.clientWidth;",
+        );
+        assert(
+            sideways <= 0,
+            "the sign prompt scrolls sideways by " + sideways + "px",
+        );
+
         const screen = await d.execute(
             `return {
              origin: document.getElementById("approve-sign-origin").textContent,