feat: add monorepo configuration and shared packages structure

Root-level setup:
- package.json with Turborepo scripts
- pnpm-workspace.yaml for workspace management
- turbo.json for build pipeline
- Common config files (.nvmrc, .prettierrc, .editorconfig)

Shared packages (packages/):
- @manacore/shared-types - Common TypeScript types
- @manacore/shared-supabase - Unified Supabase client
- @manacore/shared-utils - Date, string, async utilities
- @manacore/shared-ui - React Native UI components (placeholder)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

README.md

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+# Manacore Monorepo
+
+Monorepo containing all Manacore projects with shared packages and unified tooling.
+
+## Projects
+
+| Project | Description | Tech Stack |
+|---------|-------------|------------|
+| **maerchenzauber** | AI-powered story generation app | NestJS, Expo, SvelteKit, Astro |
+| **manacore** | Multi-app ecosystem platform | Expo, SvelteKit, Astro |
+| **manadeck** | Card/deck management app | NestJS, Expo, SvelteKit |
+| **memoro** | Voice memo & AI analysis app | Expo, SvelteKit, Astro |
+
+## Getting Started
+
+### Prerequisites
+
+- Node.js 20+
+- pnpm 9.15.0+
+
+### Installation
+
+```bash
+# Install pnpm globally (if not installed)
+npm install -g pnpm
+
+# Install all dependencies
+pnpm install
+```
+
+### Development
+
+```bash
+# Start all projects in dev mode
+pnpm run dev
+
+# Start a specific project
+pnpm run maerchenzauber:dev
+pnpm run manacore:dev
+pnpm run manadeck:dev
+pnpm run memoro:dev
+
+# Build all projects
+pnpm run build
+
+# Run tests
+pnpm run test
+
+# Type check
+pnpm run type-check
+
+# Format code
+pnpm run format
+```
+
+## Shared Packages
+
+Located in `packages/`:
+
+| Package | Description |
+|---------|-------------|
+| `@manacore/shared-types` | Common TypeScript types |
+| `@manacore/shared-supabase` | Unified Supabase client |
+| `@manacore/shared-utils` | Utility functions (date, string, async) |
+| `@manacore/shared-ui` | React Native UI components |
+
+### Using Shared Packages
+
+```typescript
+// In any project
+import { User, ApiResponse } from '@manacore/shared-types';
+import { createSupabaseClient } from '@manacore/shared-supabase';
+import { formatDate, truncate, retry } from '@manacore/shared-utils';
+```
+
+## Repository Structure
+
+```
+manacore-monorepo/
+├── packages/                 # Shared packages
+│   ├── shared-types/         # TypeScript types
+│   ├── shared-supabase/      # Supabase utilities
+│   ├── shared-utils/         # Common utilities
+│   └── shared-ui/            # React Native components
+├── maerchenzauber/           # Storyteller project
+├── manacore/                 # Manacore apps project
+├── manadeck/                 # ManaDeck project
+├── memoro/                   # Memoro project
+├── turbo.json                # Turborepo configuration
+├── pnpm-workspace.yaml       # Workspace configuration
+└── package.json              # Root package
+```
+
+## Tooling
+
+- **Package Manager:** pnpm 9.15.0
+- **Build System:** Turborepo
+- **Formatting:** Prettier
+- **Node Version:** 20 (see .nvmrc)
+
+## Adding Dependencies
+
+```bash
+# Add to root (dev tools)
+pnpm add -D <package> -w
+
+# Add to specific project
+pnpm add <package> --filter maerchenzauber
+
+# Add to shared package
+pnpm add <package> --filter @manacore/shared-utils
+```
+
+## Contributing
+
+1. Create a feature branch
+2. Make changes
+3. Run `pnpm run format` and `pnpm run type-check`
+4. Commit with conventional commit messages
+5. Create pull request
+
+## License
+
+Private - All rights reserved