feat(ui): app sessions overlay the current page in every display mode

Launching an app (or opening a tx in mempool from Home/wallet/channels) used
to router.push the app-session page in overlay/fullscreen modes, swapping the
page underneath — confusing and lossy. All display modes are now store-driven:
panel renders beside the page, overlay/fullscreen render above it (teleported
to body), and the route never changes. Deep-link paths (/tx/<hash>) ride along
via the launcher's panelPath instead of a route query; closing always returns
exactly where the user was. The app-session route stays for direct links.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

neode-ui/src/views/appSession/appSessionConfig.ts

@@ -82,7 +82,11 @@ export function resolveAppUrl(id: string, routeQueryPath?: string, runtimeUrl?:
   // mempool). Non-demoable apps fall through to a generic notice page.
   if (IS_DEMO) {
     const base = demoAppUrl(id)
-    if (base) return routeQueryPath ? base + routeQueryPath : base
+    if (base) {
+      if (!routeQueryPath) return base
+      // Join without a double slash (/app/mempool/ + /tx/x → /app/mempool/tx/x)
+      return base.replace(/\/+$/, '') + (routeQueryPath.startsWith('/') ? routeQueryPath : '/' + routeQueryPath)
+    }
     return `/app/${id}/`
   }