fix(ui): pin the OPERATIONS tab bar while panel content scrolls (#31)

The TabsList is now position:sticky top:0 with a z-index above the panel
content. In wide mode it pins to the top of the OPERATIONS scroll area
(#21's center-pane scroller); in narrow mode, where the body scrolls and
there is no inner scroll container, it pins to the viewport. The existing
opaque background keeps scrolled content from showing through.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "space-wanderer",
-  "version": "0.9.7",
+  "version": "0.9.8",
   "private": true,
   "scripts": {
     "dev": "next dev -p 3000",