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/project-shell.tsx

@@ -11,6 +11,7 @@ interface ProjectShellProps {
   workspace: string;
   projectId: string;
   projectName: string;
+  projectDescription?: string;
   projectStatus?: string;
   projectProgress?: number;
   discoveryPhase?: number;
@@ -84,6 +85,7 @@ export function ProjectShell({
   workspace,
   projectId,
   projectName,
+  projectDescription,
   projectStatus,
   projectProgress,
   discoveryPhase = 0,
@@ -137,6 +139,16 @@ export function ProjectShell({
                   </h2>
                   <StatusTag status={projectStatus} />
                 </div>
+                {projectDescription && (
+                  <p style={{
+                    fontSize: "0.75rem", color: "#a09a90", marginTop: 1,
+                    fontFamily: "Outfit, sans-serif",
+                    overflow: "hidden", textOverflow: "ellipsis", whiteSpace: "nowrap",
+                    maxWidth: 400,
+                  }}>
+                    {projectDescription}
+                  </p>
+                )}
               </div>
             </div>
             <div style={{