!feat : Implement otc contract

[anilcse]

Decentralized OTC Platform Implementation

This PR implements a CosmWasm smart contract for decentralized OTC trading. The platform enables sellers to create custom OTC deals with flexible discount rates and allows buyers to participate through a bidding mechanism with price protection features.

Overview

• Implements core OTC trading functionality
• Adds flexible discount mechanism
• Ensures atomic settlement of trades
• Includes comprehensive test coverage
• Implements platform fee mechanism

Features Checklist

• Deal Creation

  • Custom token support
  • Configurable discount rates
  • Minimum price protection
  • Minimum cap requirements
  • Customizable bidding timeframes
  • Platform fee collection

• Bid Management

  • Place new bids
  • Update existing bids
  • Withdraw bids
  • Maximum price protection
  • Discount rate specification
  • Bid validation checks

• Deal Settlement

  • Automatic bid sorting by discount
  • Priority for lowest discount bids
  • Partial fill handling
  • Atomic settlement
  • Automatic refunds
  • Min-cap validation

• Platform Security

  • Input validation
  • Overflow protection
  • Time-based constraints
  • Access control
  • Error handling

• Developer Experience

  • Comprehensive documentation
  • Clear error messages
  • Helper functions
  • Unit tests
  • Code organization

Testing Coverage

• Unit tests for core functionality
• Integration tests for complex scenarios
• Error case handling tests

Next Steps

• Add more complex test scenarios
• Implement optional deal cancellation
• Add deal modification capabilities
• Enhance monitoring and analytics
• Add multi-token support for payments

Breaking Changes

None. This is a new contract implementation.

Dependencies

• CosmWasm ^1.1.0
• cw-storage-plus ^0.15.1
• cw20 ^0.15.1

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Please review the implementation with special attention to:

1. Deal settlement logic
2. Fee calculation mechanism
3. Error handling approach
4. Test coverage completeness