feat: show tenancy scope (Org → Chapter) in chapter & member portals

Surface where the logged-in user sits in the hierarchy via a ScopeCard
in the sidebar, below the brand mark.

API:
- Enrich chapter login/me responses with tenantName + organization
  (LoginResponse.admin, AdminProfile types updated)
- Add GET /my/scope returning member's chapter + organization

Web:
- ScopeCard component (Organisation row + Chapter row, themed icons)
- Chapter portal: scope from auth context, blue accent
- Member portal: scope fetched server-side in layout, emerald accent
- PortalShell gains a `scope` slot rendered under the brand

Org and admin portals intentionally omit it — org IS the scope, admin is
platform-wide.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/web/app/_components/portal-shell.tsx

@@ -34,6 +34,8 @@ interface PortalShellProps {
   theme: PortalTheme;
   navItems: PortalNavItem[];
   user?: PortalUser;
+  /** Optional scope indicator (e.g. <ScopeCard/>) rendered below the brand */
+  scope?: React.ReactNode;
   loading: boolean;
   authed: boolean;
   onLogout: () => void;
@@ -41,7 +43,7 @@ interface PortalShellProps {
 }
 
 export function PortalShell({
-  portalName, theme, navItems, user, loading, authed, onLogout, children,
+  portalName, theme, navItems, user, scope, loading, authed, onLogout, children,
 }: PortalShellProps) {
   const pathname = usePathname();
   const t = PORTAL_THEMES[theme];
@@ -61,6 +63,9 @@ export function PortalShell({
           </div>
         </div>
 
+        {/* Scope */}
+        {!loading && authed && scope}
+
         {/* Nav */}
         <nav className="flex-1 overflow-y-auto p-3 space-y-1">
           {loading ? (