feat(ui): re-theme Team Memory graph to match the shadcn app

The app is light shadcn; GraphView was hardcoded dark-Bauhaus and clashed.
Re-theme to shadcn tokens (var(--card)/--foreground/--muted-foreground/
--border, var(--primary) for active) so the panel is theme-aware (light now,
follows dark mode if toggled) and native to the command-center. Node-kind
encoding kept (shapes + light-readable hues); labels are sentence-case.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/graph.md

@@ -79,7 +79,7 @@ Additive routes in `backend/src/server.ts` (shared file — additive only).
 - `backend/src/graph/store.ts` — `loadPodGraph`, `seedGraph`, `reachFrom` (`$graphLookup`)
 - `backend/src/graph/seed.ts` — `pnpm graph:seed` (writes demo into `team_model` + graph collections)
 - `frontend/src/lib/graph.ts` — `fetchPodGraph(podId)`
-- `frontend/src/components/GraphView.tsx` — dark-Bauhaus SVG graph (toggle from `App.tsx`)
+- `frontend/src/components/GraphView.tsx` — shadcn-themed SVG graph (theme-aware; toggle from `App.tsx`)
 
 ## Demo-first plan