feat: Add comprehensive API documentation with OpenAPI spec

[wangxiaofei860208-source]

Summary

This PR adds comprehensive API documentation for the PrivacyLayer privacy pool smart contract, addressing issue #62.

Deliverables

✅ OpenAPI 3.0.3 Specification (docs/openapi.yaml - 650+ lines)

• All contract endpoints documented (initialize, deposit, withdraw, view functions, admin functions)
• Complete request/response schemas
• Error codes and descriptions
• Authentication requirements
• Interactive Swagger UI compatible

✅ Postman Collection (docs/postman_collection.json)

• Ready-to-import collection with all endpoints
• Environment variables configured
• Example requests for all operations

✅ Code Examples (docs/examples/typescript-example.ts)

• TypeScript/JavaScript integration examples
• Deposit and withdrawal flows
• View function queries
• Error handling patterns

✅ Documentation README (docs/README.md)

• Setup instructions for Swagger UI and Redoc
• Postman import guide
• API versioning information
• Security considerations

API Coverage

Initialization

• POST /initialize - Initialize the privacy pool

Core Operations

• POST /deposit - Deposit into shielded pool
• POST /withdraw - Withdraw using ZK proof

View Functions

• GET /get_root - Get current Merkle root
• GET /deposit_count - Get total deposits
• GET /is_known_root - Check root validity
• GET /is_spent - Check nullifier status
• GET /get_config - Get pool configuration

Admin Functions

• POST /pause - Pause the pool
• POST /unpause - Unpause the pool
• POST /set_verifying_key - Update verifying key

Testing

View the OpenAPI spec:

1. Visit https://editor.swagger.io/
2. Paste contents of docs/openapi.yaml
3. Explore interactive documentation

Import Postman collection:

1. Open Postman
2. Import docs/postman_collection.json
3. Configure environment variables

Closes

Closes #62

🤖 Generated with Claude Code