NetworkView: API routing fix, logout button, audit trail, port/notes editor tracking

- Fix frontend API base path (VITE_API_BASE env var, GraphPage hardcoded /api)
- Add logout button to NetworkView sidebar (clears portal SSO)
- Add AuditTrail component: inline change history on all entity pages
- DB migration: add updated_at, last_edited_by to ports table
- DB migration: add notes_last_edited_by, notes_updated_at to all entity tables
- Backend: track actor on port create/update; notes editor on entity PUT
- Frontend: extend types, MarkdownEditor shows last editor, port modal/list show last editor
- Fix port CREATE TABLE definition to include new columns upfront
- Add try/catch in handleSavePort to surface API errors in modal

NetworkView/frontend/src/components/Sidebar.tsx

@@ -229,6 +229,13 @@ export default function Sidebar() {
         <Link to="/settings" className={`sidebar-footer-link ${isActive('/settings') ? 'active' : ''}`}>
           ⚙ Settings
         </Link>
+        <button
+          className="sidebar-footer-link sidebar-logout-btn"
+          onClick={() => { window.location.href = (import.meta.env.VITE_PORTAL_LOGOUT_URL as string | undefined) ?? '/logout'; }}
+          title="Log out of NetworkView and the Enterprise Portal"
+        >
+          ⏻ Logout
+        </button>
       </div>
     </aside>
   );