Theseus 0.3.64: cleaner window title — "Theseus Navigator — is not responding", not the tagline

Windows's "App is not responding" dialog and Task Manager read FileDescription
from the exe's VERSIONINFO resource, which electron-builder sets from
package.json's description. The marketing tagline sat there, so a frozen tab
produced "Theseus Navigator — a browser that follows the thread. By Silent
Mode, a Deviant project. is not responding". Override via build.extraMetadata
so only the built asar's description is clipped to "Theseus Navigator"; the
source description stays as-is for npm metadata.

(The "not responding" freeze itself is fixed in 0.3.63 by the lazy tab
restore — users still on 0.3.62 will see it until they take 0.3.63.)

package.json

@@ -1,6 +1,6 @@
 {
   "name": "theseus-navigator",
-  "version": "0.3.63",
+  "version": "0.3.64",
   "license": "MPL-2.0",
   "description": "Theseus Navigator — a browser that follows the thread. By Silent Mode, a Deviant project.",
   "author": "Silent Mode",
@@ -43,6 +43,9 @@
     "appId": "st.silentmode.theseus",
     "productName": "Theseus Navigator",
     "artifactName": "TheseusNavigator-${version}-${arch}.${ext}",
+    "extraMetadata": {
+      "description": "Theseus Navigator"
+    },
     "directories": {
       "output": "dist-public"
     },