topbar: the theme toggle comes from the package, not a deleted file

The commit that removed the shadow fork said ThemeToggle was deleted outright
because nothing imported it. That is true on the lineage it was written on,
where a later change had already taken the toggle out of the topbar. It is NOT
true here: this topbar still renders one, so deleting the file left a dangling
import.

@hanzo/ui/product exports a ThemeToggle whose no-prop form is specifically the
Next path — it falls back to @hanzogui/next-theme and degrades to a DOM class
toggle if that cannot load — so <ThemeToggle /> reads exactly as before.

Typecheck clean; 3199 passing, 8 skipped.

src/entry/dashboard.tsx

@@ -100,7 +100,6 @@ import { useDetailPane } from '~/components/DetailPane'
 import { ProductCustomize, ManagePins } from '~/components/SidebarCustomize'
 import { SlideOver } from '~/components/ui/SlideOver'
 import { ProductIcon } from '~/components/ui/ProductIcon'
-import { ThemeToggle } from '~/components/ui/ThemeToggle'
 import { SystemStatusBadge } from '~/components/ui/SystemStatusBadge'
 import { Breadcrumbs } from '~/components/ui/Breadcrumbs'
 import { SidebarBrand } from '~/components/SidebarBrand'
@@ -113,6 +112,7 @@ import { ContextSwitcher } from '~/components/ContextSwitcher'
 import { useFloatingChat, DockedChatPanel } from '~/components/FloatingChat'
 import { WorkbenchDock } from '~/components/workbench/Workbench'
 import { Z } from '~/lib/z'
+import { ThemeToggle } from '@hanzo/ui/product'
 
 const EXPANDED_W = 264
 const COLLAPSED_W = 64