NextGraph integration (WIP), broker banner, and feature-based architecture

- Add NextGraph data layer with @ng-org/orm, SHEX shapes (Event, UserProfile,
  Participation), session management, and FestipodDataContext with dual-mode
  operation (connected via NextGraph or local seed data)
- Add BrokerBanner and NgStatus components showing connection status
- Refactor to feature-based architecture: organize code by business domain
  (event, user, home, auth, workshop, meeting, notification) instead of
  technical layer. Modules only import from shared/, never from each other
- Collocate BDD features and step definitions with their modules: event-specific
  steps in event/steps/, user steps in user/steps/, shared generic steps remain
  in shared/steps/
- Set up multi-layer BDD structure (frontend/backend/e2e steps per module)
- Add project documentation (AGENTS.md, .project/knowledge/)

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

.project/knowledge/architecture.md

@@ -0,0 +1,84 @@
+# Architecture
+
+Feature-based architecture where code is organized by business domain (module), not by technical layer.
+
+## Module Structure
+
+```
+src/modules/
+  event/          # 7 screens, 5 features — events CRUD, discovery, participants, meeting points
+  user/           # 5 screens, 11 features — profiles, friends, sharing
+  home/           # 2 screens — dashboard, settings
+  auth/           # 2 screens — login, welcome/onboarding
+  workshop/       # 0 screens, 6 features — workshop/atelier specs (future)
+  meeting/        # 0 screens, 1 feature — meeting point specs
+  notification/   # 0 screens, 3 features — notification specs
+```
+
+Each module can contain:
+- `screens/` — React screen components
+- `features/` — Gherkin `.feature` files (BDD specs)
+- `steps/{frontend,backend,e2e}/` — Cucumber step definitions by layer
+
+## Import Rules
+
+**Modules only import from `shared/` — never from each other.**
+
+```
+src/modules/event/screens/EventDetailScreen.tsx
+  ✅ import from '../../../shared/components/sketchy'
+  ✅ import from '../../../shared/context/FestipodDataContext'
+  ✅ import from '../../../screens' (registry types)
+  ❌ import from '../../user/screens/...'
+```
+
+## Shared Layer
+
+`src/shared/` contains everything reusable across modules:
+
+| Directory | Contents |
+|-----------|----------|
+| `components/sketchy/` | Hand-drawn UI library (Button, Card, Avatar, Header, NavBar, etc.) |
+| `components/ui/` | Shadcn/Radix components (used only in prototyping tool) |
+| `context/` | ThemeContext, NextGraphContext, FestipodDataContext |
+| `data/` | User stories (`index.ts`), auto-generated `features.ts`, `testResults.ts`, `seedData.ts`, `types.ts` |
+| `hooks/` | `useShapeWithDefaults` (NextGraph) |
+| `shapes/` | SHEX definitions + ORM TypeScript bindings |
+| `utils/` | `ngSession.ts`, `ngBootstrap.ts` |
+| `steps/frontend/` | Shared BDD step definitions (navigation, screen, form) |
+| `support/` | Cucumber `world.ts`, `hooks.ts` |
+| `types/` | `gherkin.ts` (ParsedFeature, ParsedScenario types) |
+| `lib/` | `utils.ts` (cn helper for Tailwind) |
+
+## App Shell
+
+`src/app/` is the prototyping tool — not part of the Festipod app itself:
+
+- `App.tsx` — Root: ThemeProvider > NextGraphProvider > FestipodDataProvider > RouterProvider
+- `router.tsx` — Hash-based routing: `#/` (gallery), `#/demo/{screenId}`, `#/specs/{featureId}`
+- `frontend.tsx` — React entry point (referenced from `src/index.html`)
+- `components/Gallery.tsx` — Screen preview grid
+- `components/DemoMode.tsx` — Interactive mockup viewer with sidebar navigation
+- `components/specs/` — BDD specs browser (SpecsPage, FeatureView, GherkinHighlighter)
+
+## Screen Registry
+
+`src/screens/index.ts` is the central registry that imports all screens from all modules and exports:
+- `screenGroups` — Grouped by domain (Accueil, Evenements, Utilisateur, General)
+- `screens` — Flat list
+- `getScreen(id)` — Lookup by ID
+- `ScreenProps` interface — `{ navigate: (screenId: string) => void }`
+
+## Entry Points
+
+| File | Purpose |
+|------|---------|
+| `src/index.ts` | Bun.serve() — HTTP server, serves index.html + cucumber report |
+| `src/index.html` | HTML entry, loads `src/app/frontend.tsx` |
+| `src/app/frontend.tsx` | React root, renders `<App />` |
+
+## Build
+
+- Dev: `bun --hot src/index.ts` (via `bun run dev`)
+- Prod: `bun run build.ts` — Bun bundler + Tailwind plugin → `dist/`
+- Path alias: `@/*` → `./src/*` (tsconfig)