Fix local store detection and related issues

- Add localStore into the stash because it's used in templates
- Hide the Channels button for non-local stores because the link 404s
  anyway
- Fix a style issue when having popovers in dark mode

src/root/static/css/hydra.css

@@ -186,7 +186,7 @@ a.squiggle:hover {
     html {
         background-color: #1f1f1f;
     }
-    body, div.popover {
+    body, div.popover, div.popover-body {
         background-color: #1f1f1f;
         color: #fafafa !important;
     }