feat(graph): demo-ready materializer + per-pod Team memory action

Materializer (live.ts) — cut demo-pod from 110 -> 22 nodes:
- cap to 8 recent collisions; collapse repeats by memorySignature
- collapse interventions to one (most recent) per collision
- filter junk 'files' (URLs, env vars, browser/app names, scratch/test) to
  real source paths only
- prune test-artifact engineers (a/b/verify/codex-check/-testrepo) + any node
  orphaned by that
- collisions referenced by accepted outcomes bypass the cap so the learned_from
  money path never drops; risk-paths metric counts distinct signatures

UI: per-pod 'Team memory' action on each PodCard's menu (replaces the header
button that always opened pods[0]).

Verified against live demo-pod data (joins connect); typechecks clean.

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

frontend/src/App.tsx

@@ -268,10 +268,6 @@ export default function App() {
                 <ShieldCheckIcon data-icon="inline-start" />
                 Privacy-limited
               </Badge>
-              <Button variant="outline" onClick={() => setGraphPodId(pods[0]?.id ?? 'demo-pod')}>
-                <BrainCircuitIcon data-icon="inline-start" />
-                Team memory
-              </Button>
               <Button variant="outline" onClick={() => void refresh()} disabled={loading}>
                 <RefreshCwIcon data-icon="inline-start" />
                 Refresh
@@ -342,6 +338,7 @@ export default function App() {
                       onRemoveMember={handleRemoveMember}
                       onUpdate={handleUpdate}
                       onDelete={handleDelete}
+                      onOpenGraph={setGraphPodId}
                     />
                   ))}
                 </div>