feat(ui): move preview device toggles into the global nav rail

vibn-frontend/app/[workspace]/project/[projectId]/(home)/preview/page.tsx

@@ -5,6 +5,7 @@ import { useEffect, useLayoutEffect, useRef, useState } from "react";
 import { Loader2 } from "lucide-react";
 import { useAnatomy } from "@/components/project/use-anatomy";
 import { usePreviewBridge } from "@/components/project/preview-bridge-context";
+import { usePreviewToolbarStore } from "@/components/project/preview-toolbar/preview-toolbar-state";
 
 const SAME_ORIGIN_SANDBOX =
   "allow-scripts allow-forms allow-same-origin allow-popups allow-modals allow-downloads" as const;
@@ -32,7 +33,7 @@ export default function PreviewTab() {
   const bridge = usePreviewBridge();
   const origin = typeof window !== "undefined" ? window.location.origin : "";
 
-  const [deviceMode, setDeviceMode] = useState<"desktop" | "mobile">("desktop");
+  const deviceMode = usePreviewToolbarStore((s) => s.deviceMode);
 
   // Auto-select first preview on load
   useEffect(() => {
@@ -67,43 +68,6 @@ export default function PreviewTab() {
             ))}
           </select>
         )}
-        <div
-          style={{
-            display: "flex",
-            gap: 4,
-            background: "rgba(255,255,255,0.85)",
-            padding: 4,
-            borderRadius: 8,
-            border: "1px solid rgba(26,26,26,0.12)",
-          }}
-        >
-          <button
-            onClick={() => setDeviceMode("desktop")}
-            style={{
-              padding: "4px 12px",
-              borderRadius: 6,
-              fontSize: "0.8rem",
-              background:
-                deviceMode === "desktop" ? "rgba(0,0,0,0.06)" : "transparent",
-              color: deviceMode === "desktop" ? "#000" : "#666",
-            }}
-          >
-            Desktop
-          </button>
-          <button
-            onClick={() => setDeviceMode("mobile")}
-            style={{
-              padding: "4px 12px",
-              borderRadius: 6,
-              fontSize: "0.8rem",
-              background:
-                deviceMode === "mobile" ? "rgba(0,0,0,0.06)" : "transparent",
-              color: deviceMode === "mobile" ? "#000" : "#666",
-            }}
-          >
-            Mobile
-          </button>
-        </div>
       </div>
 
       <div