Add route for command results in popup window (#93)

* feat: Add pop-out command route for standalone window rendering

Add a new /run route that allows windows to be opened in separate
browser windows/tabs without affecting the main workspace layout.

Changes:
- Add RunCommandPage component for /run?cmd=<command> route
- Add Pop Out button to WindowToolbar (ExternalLink icon)
- Parse command from URL query parameter and render result
- Construct minimal WindowInstance for rendering
- Display command string in header with clean minimal UI

This enables users to pop out any window into a separate browser
context while maintaining the main workspace layout, useful for
multi-monitor setups or keeping reference windows visible.

* refactor: Remove header from pop-out command page

Simplify RunCommandPage to only show the window renderer without
any additional UI chrome. This provides a cleaner, more focused
experience for popped-out windows.

* refactor: Move pop-out action to window menu dropdown

Move the pop-out button from a standalone icon to the three-dot
menu dropdown to reduce toolbar clutter. The menu now always
appears since pop-out is always available.

* feat: Add AppShell header to pop-out command page

Wrap RunCommandPage with AppShell (hideBottomBar) to show the header
with user menu and command launcher, matching the behavior of NIP-19
preview pages.

When a command is launched from the /run page, it navigates to the
main dashboard (/) where the window system exists.

---------

Co-authored-by: Claude <noreply@anthropic.com>

src/root.tsx

@@ -3,6 +3,7 @@ import { AppShell } from "./components/layouts/AppShell";
 import DashboardPage from "./components/pages/DashboardPage";
 import SpellbookPage from "./components/pages/SpellbookPage";
 import Nip19PreviewRouter from "./components/pages/Nip19PreviewRouter";
+import RunCommandPage from "./components/pages/RunCommandPage";
 
 const router = createBrowserRouter([
   {
@@ -13,6 +14,14 @@ const router = createBrowserRouter([
       </AppShell>
     ),
   },
+  {
+    path: "/run",
+    element: (
+      <AppShell hideBottomBar>
+        <RunCommandPage />
+      </AppShell>
+    ),
+  },
   {
     path: "/preview/:actor/:identifier",
     element: (