Redesign the interface

Deep blue-black theme with a violet-to-cyan accent, frosted floating
panels, self-hosted Inter, a welcome screen with a call to action, a
card-style inspector, accent tabs and toggles, animated progress, and
a restyled open dialog. In 3D the WebGL walls are now lit per side
with a darker foot so buildings read as solids, and the canvas clears
to transparent over the new background. Renamed to CodeNavigator.

main_test.go

@@ -240,7 +240,7 @@ func TestRoutesAndHeaders(t *testing.T) {
 		t.Fatalf("preflight = %d %v", res.StatusCode, res.Header)
 	}
 
-	for path, contentType := range map[string]string{"/": "text/html", "/api.mjs": "text/javascript", "/styles.css": "text/css", "/config.js": "text/javascript"} {
+	for path, contentType := range map[string]string{"/": "text/html", "/api.mjs": "text/javascript", "/styles.css": "text/css", "/config.js": "text/javascript", "/inter-latin.woff2": "font/woff2"} {
 		res, err := http.Get(c.url + path)
 		if err != nil {
 			t.Fatal(err)