refactor(data): route entities by scope via the SDK — no store ids in the app

Festipod now treats @ng-eventually/client as a finished NextGraph SDK: the app
decides only each entity's logical scope (events/PdR public, profiles/
participations protected, settings private) and calls the lib by scope. The old
mono-store default and the FESTIPOD_MULTISTORE path collapse into ONE scope path.

Removed every physical-store leak from the app data-plane (ngGraph, registration,
FestipodDataContext, NextGraphContext, useShapeWithDefaults): no more
did🆖${store_id} construction. The session is handed to the lib only at the
sanctioned injection point (ngSession/configureStoreRegistry). Product behavior
unchanged. @data 20/20; build + tsc clean.

(_debt.md included; the T03.e doctrine pass settles accumulated doc-debt.)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.project/concepts/app-security/_debt.md

@@ -0,0 +1,9 @@
+# Doc-debt — app-security
+
+> Presence of a block = doc to update. Processed → delete the block; no blocks left → delete this file.
+> One block = one "big change": `why` + `files` + `verify` (leaves to review).
+
+## Block: T03.g — NextGraphContext ne surface plus les store-ids
+- **why**: `NextGraphContext` ne journalise/expose plus les trois store-ids dans le contexte app (routés uniquement au point d'injection SDK). Renforce la doctrine "isolation déléguée au SDK, l'app ne manipule pas de store physique" — ne l'invalide pas.
+- **files**: src/shared/context/NextGraphContext.tsx
+- **verify (leaves à relire)**: knowledge_trust-model.md (confirmer : confiance dans le SDK, aucune manipulation de store côté app). Aucun changement de contenu attendu — relecture confirmatoire.