Complete Stackless parity: Activity, Deploy, Settings, header desc

- Add project description line to project header (from productVision)
- Sidebar: add Activity nav item (Projects / Activity / Settings)
- New Activity page: timeline feed with type filters (Atlas/Builds/Deploys/You)
- New Activity layout using VIBNSidebar
- Rewrite Deploy tab: Project URLs, Custom Domain, Env Vars, Deploy History
  — fully Stackless style, real data from project API, no more MOCK_PROJECT
- Rewrite Project Settings tab: remove all Firebase refs (db, auth, Firestore)
  — General (name/description), Repo link, Collaborators, Export JSON/PDF,
  — Danger Zone with double-confirm delete
  — uses /api/projects/[id] PATCH for saves

Made-with: Cursor

components/layout/vibn-sidebar.tsx

@@ -49,12 +49,13 @@ export function VIBNSidebar({ workspace }: VIBNSidebarProps) {
 
   // Derive active top-level section
   const isProjects = !activeProjectId && (pathname?.includes("/projects") || pathname?.includes("/project"));
-  const isActivity = pathname?.includes("/activity");
-  const isSettings = pathname?.includes("/settings");
+  const isActivity = !activeProjectId && pathname?.includes("/activity");
+  const isSettings = !activeProjectId && pathname?.includes("/settings");
 
   const topNavItems = [
-    { id: "projects", label: "Projects", icon: "⌗", href: `/${workspace}/projects` },
-    { id: "settings", label: "Settings", icon: "⚙", href: `/${workspace}/settings` },
+    { id: "projects",  label: "Projects",  icon: "⌗", href: `/${workspace}/projects` },
+    { id: "activity",  label: "Activity",  icon: "↗", href: `/${workspace}/activity` },
+    { id: "settings",  label: "Settings",  icon: "⚙", href: `/${workspace}/settings` },
   ];
 
   const userInitial = session?.user?.name?.[0]?.toUpperCase()
@@ -106,7 +107,8 @@ export function VIBNSidebar({ workspace }: VIBNSidebarProps) {
       {/* Top nav */}
       <div style={{ padding: "4px 10px" }}>
         {topNavItems.map((n) => {
-          const isActive = n.id === "projects" ? isProjects && !activeProjectId
+          const isActive = n.id === "projects" ? isProjects
+            : n.id === "activity" ? isActivity
             : n.id === "settings" ? isSettings
             : false;
           return (