Implement Mining Account Type

Summary

Create a specialized account type for managing mining contexts and configurations.

Background

Third-party applications need a dedicated account type to manage their mining parameters, epoch state, and reward configuration.

Requirements

Define MiningAccount as a data account extension
Store mining configuration and state
Support epoch management
Track registered miners and rewards

Implementation Details

type MiningAccount struct {
    DataAccount
    
    Config MiningConfig
    State  MiningState
}

type MiningConfig struct {
    Active          bool
    EpochDuration   uint64
    TopN            uint16
    RewardToken     *url.URL
    RewardAmount    uint64
    RewardAccount   *url.URL
    MinSubmissions  uint16
}

type MiningState struct {
    CurrentEpoch     uint64
    LastDNAnchor     [32]byte
    ActiveMiners     uint32
    TotalDistributed uint64
    CurrentQueue     []MiningEntry  // Top N for current epoch
}

Acceptance Criteria

MiningAccount type defined in schema
Configuration storage and retrieval
State management methods
Epoch transition logic
Priority queue management
Unit tests for account operations
Integration with data account infrastructure

Dependencies

Depends on: #3668 (Mining Transaction Type)

Epic: &37
Specification: 32-lxr-mining.md