fix: TOC panel never auto-opens on login — always starts closed

- Removed localStorage restore of obsigate-right-sidebar-visible on init
- TOC only opens when user clicks the TOC button in a document
- Width preference still restored from localStorage

frontend/app.js

@@ -1099,13 +1099,9 @@
     },
 
     loadState() {
-      const savedVisible = localStorage.getItem("obsigate-right-sidebar-visible");
+      // Always start closed on login/refresh — user must explicitly toggle TOC
       const savedWidth = localStorage.getItem("obsigate-right-sidebar-width");
 
-      if (savedVisible !== null) {
-        rightSidebarVisible = savedVisible === "true";
-      }
-
       if (savedWidth) {
         rightSidebarWidth = parseInt(savedWidth) || 280;
       }