fix: navigator.languages should include base language per spec

Per the HTML spec, navigator.languages should return the user's
preferred languages. Most browsers return at least ["en-US", "en"]
to include the base language tag alongside the regional variant.

This matches Chrome, Firefox, and Safari behavior and improves
compatibility with sites that check for language negotiation.

Author: evan108108

src/browser/tests/navigator/navigator.html

@@ -15,8 +15,9 @@
   testing.expectEqual(true, validPlatforms.includes(navigator.platform));
   testing.expectEqual('en-US', navigator.language);
   testing.expectEqual(true, Array.isArray(navigator.languages));
-  testing.expectEqual(1, navigator.languages.length);
+  testing.expectEqual(2, navigator.languages.length);
   testing.expectEqual('en-US', navigator.languages[0]);
+  testing.expectEqual('en', navigator.languages[1]);
   testing.expectEqual(true, navigator.onLine);
   testing.expectEqual(true, navigator.cookieEnabled);
   testing.expectEqual(true, navigator.hardwareConcurrency > 0);

src/browser/webapi/Navigator.zig

@@ -40,8 +40,8 @@ pub fn getUserAgent(_: *const Navigator, page: *Page) []const u8 {
     return page._session.browser.app.config.http_headers.user_agent;
 }
 
-pub fn getLanguages(_: *const Navigator) [1][]const u8 {
-    return .{"en-US"};
+pub fn getLanguages(_: *const Navigator) [2][]const u8 {
+    return .{ "en-US", "en" };
 }
 
 pub fn getPlatform(_: *const Navigator) []const u8 {