move global search input to a general location

- create a global search store
- create a half-baked context menu store
-

src/assets/css/global.scss

@@ -87,7 +87,7 @@ button {
   grid-template-rows: 3rem 1fr 1fr;
   grid-auto-flow: row;
   grid-template-areas:
-    "l-sidebar nav r-sidebar"
+    "l-sidebar nav search-input"
     "l-sidebar content r-sidebar"
     "l-sidebar content r-sidebar"
     "l-sidebar bottom-bar tabs";
@@ -103,6 +103,11 @@ button {
   }
 }
 
+.gsearch-input {
+  grid-area: search-input;
+  border-left: solid 1px $gray;
+}
+
 .topnav {
   grid-area: nav;
 }