Fix clippy warnings in bitcell-node

- Remove unused import COIN from blockchain.rs
- Remove unused import SecretKey from main.rs
- Remove empty line after doc comment in miner.rs
- Remove empty line after doc comment in blockchain.rs

Co-authored-by: Steake <530040+Steake@users.noreply.github.com>

Author: Copilot

crates/bitcell-node/src/blockchain.rs

@@ -5,11 +5,10 @@
 ///! - Block validation including signature, VRF, and transaction verification
 ///! - Transaction indexing for efficient lookups
 ///! - State management with Merkle tree root computation
-
 use crate::{Result, MetricsRegistry};
 use bitcell_consensus::{Block, BlockHeader, Transaction, BattleProof};
 use bitcell_crypto::{Hash256, PublicKey, SecretKey};
-use bitcell_economics::{COIN, INITIAL_BLOCK_REWARD, HALVING_INTERVAL, MAX_HALVINGS};
+use bitcell_economics::{INITIAL_BLOCK_REWARD, HALVING_INTERVAL, MAX_HALVINGS};
 use bitcell_state::StateManager;
 use std::sync::{Arc, RwLock};
 use std::collections::HashMap;

crates/bitcell-node/src/main.rs

@@ -1,7 +1,6 @@
 //! BitCell node binary
 
 use bitcell_node::{NodeConfig, ValidatorNode, MinerNode};
-use bitcell_crypto::SecretKey;
 use clap::{Parser, Subcommand};
 use std::path::PathBuf;
 

crates/bitcell-node/src/miner.rs

@@ -1,5 +1,4 @@
 ///! Miner node implementation
-
 use crate::{NodeConfig, Result, MetricsRegistry, Blockchain, TransactionPool, NetworkManager};
 use bitcell_crypto::SecretKey;
 use bitcell_ca::{Glider, GliderPattern};