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/data-layer.md

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+# Data Layer
+
+NextGraph-backed local-first data with fallback to local state for demo/disconnected mode.
+
+## Overview
+
+The app has two data modes:
+1. **Connected** — NextGraph ORM shapes (P2P, encrypted, local-first)
+2. **Disconnected/Demo** — Local React state seeded from `seedData.ts`
+
+All screens use `useFestipodData()` hook regardless of mode.
+
+## NextGraph Stack
+
+```
+@ng-org/web          # Browser WASM runtime
+@ng-org/orm          # RDF shape-based ORM
+@ng-org/shex-orm     # SHEX → TypeScript code generation
+@ng-org/alien-deepsignals  # Reactive signals bridge
+```
+
+Packages installed from local tarballs in `.ng-tarballs/`.
+
+## SHEX Shapes
+
+`src/shared/shapes/shex/festipodShapes.shex` defines:
+- **Event** — title, description, dates, location, themes, participants
+- **UserProfile** — name, username, bio, city, visibility
+- **Participation** — links event + user, confirmation status
+
+ORM bindings in `src/shared/shapes/orm/`:
+- `festipodShapes.schema.ts` — Schema registration
+- `festipodShapes.shapeTypes.ts` — Shape type constants
+- `festipodShapes.typings.ts` — TypeScript interfaces
+
+Regenerate with `bun run build:orm`.
+
+## Context Providers
+
+### NextGraphContext (`src/shared/context/NextGraphContext.tsx`)
+- Connection lifecycle: `disconnected` → `connecting` → `connected` | `error`
+- Auto-initializes via `initNg()` from `src/shared/utils/ngSession.ts`
+- Provides session with store IDs (private, protected, public)
+
+### FestipodDataContext (`src/shared/context/FestipodDataContext.tsx`)
+- Wraps NextGraph shapes with `useShapeWithDefaults()` hook
+- CRUD: `createEvent()`, `updateEvent()`, `joinEvent()`, `leaveEvent()`, etc.
+- Exposes `useFestipodData()` hook consumed by all screens
+- `selectedEventId` state for cross-screen event navigation
+- Falls back to seed data when disconnected
+
+## Data Types
+
+`src/shared/data/types.ts`:
+- `FpEventData` — id, title, date, location, distance, themes, etc.
+- `FpUserData` — id, name, username, bio, city, counts
+- `FpParticipationData` — eventId + userId + confirmed
+- `FpMeetingPointData` — eventId, location, time, host (local-only)
+- `FpFriendshipData` — userId + friendId (local-only)
+
+## Seed Data
+
+`src/shared/data/seedData.ts`:
+- 10 users (Marie Dupont = current user, `user-1`)
+- Multiple events with dates, locations, themes
+- Participations, meeting points, friendships
+- `CURRENT_USER_ID = 'user-1'`