Chore/add setup and contributing docs (#90)

* chore: add dev setup documentation

* Add agents.md files

* simplify contributing documentation

ui/.env.example

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+NEXT_PUBLIC_BACKEND_URL=http://localhost:8000
+BACKEND_URL=http://localhost:8000
+
+NEXT_PUBLIC_NODE_ENV=development
+NEXT_PUBLIC_DEPLOYMENT_MODE: "oss"
+NEXT_PUBLIC_AUTH_PROVIDER="local"

ui/AGENTS.md

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+# UI - Frontend Application
+
+Next.js 15 frontend for the Dograh voice AI platform.
+
+## Project Structure
+
+```
+ui/
+├── src/
+│   ├── app/          # Next.js App Router pages
+│   ├── components/   # React components
+│   ├── lib/          # Utilities and configurations
+│   ├── client/       # Auto-generated API client
+│   ├── context/      # React context providers
+│   ├── hooks/        # Custom React hooks
+│   ├── constants/    # Application constants
+│   └── types/        # TypeScript type definitions
+├── public/           # Static assets
+└── package.json
+```
+
+## Where to Find Things
+
+| Looking for...      | Go to...                                             |
+| ------------------- | ---------------------------------------------------- |
+| Pages/routes        | `src/app/` - Next.js App Router (file-based routing) |
+| Reusable components | `src/components/` - organized by feature             |
+| Base UI primitives  | `src/components/ui/` - shadcn/ui components          |
+| Workflow builder    | `src/components/flow/` - React Flow based            |
+| API calls           | `src/client/` - auto-generated from OpenAPI spec     |
+| Auth utilities      | `src/lib/auth/`                                      |
+| Helper functions    | `src/lib/utils.ts`                                   |
+| Global state        | `src/context/` - React context providers             |
+
+## Tech Stack
+
+- Next.js 15 with App Router, React 19, TypeScript
+- Tailwind CSS with shadcn/ui components
+- Zustand for state management
+- @xyflow/react for workflow builder
+- LiveKit for WebRTC voice
+
+## API Client
+
+The `src/client/` directory is auto-generated from the backend OpenAPI spec:
+
+```bash
+npm run generate-client
+```
+
+## Development
+
+```bash
+npm install
+npm run dev    # Runs on port 3000
+```

ui/CLAUDE.md

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+@AGENTS.md