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-architecture/_debt.md

@@ -0,0 +1,9 @@
+# Doc-debt — app-architecture
+
+> 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 — routage par scope (pas de changement d'archi)
+- **why**: FestipodDataContext route les entités par scope via le SDK et NextGraphContext ne surface plus les store-ids. La structure (provider stack, invariant d'imports module→shared, app shell) est inchangée — touches incidentes, pas d'évolution architecturale.
+- **files**: src/shared/context/NextGraphContext.tsx, src/shared/context/FestipodDataContext.tsx
+- **verify (leaves à relire)**: aucune — knowledge_app-shell.md / knowledge_module-structure.md inchangés. Bloc à supprimer après relecture confirmatoire.