ax(mining): rename mu to mutex in SimulatedMiner

AX Principle 1: predictable names over short names. mu → mutex
matches the same fix already applied to Manager and SettingsManager.

Co-Authored-By: Charon <charon@lethean.io>

pkg/mining/simulated_miner.go

@@ -36,7 +36,7 @@ type SimulatedMiner struct {
 	shares         int
 	rejected       int
 	logs           []string
-	mu             sync.RWMutex
+	mutex          sync.RWMutex
 	stopChan       chan struct{}
 	poolName       string
 	difficultyBase int
@@ -100,9 +100,9 @@ func (m *SimulatedMiner) Uninstall() error {
 
 // if err := miner.Start(config); err != nil { /* already running */ }
 func (m *SimulatedMiner) Start(config *Config) error {
-	m.mu.Lock()
+	m.mutex.Lock()
 	if m.Running {
-		m.mu.Unlock()
+		m.mutex.Unlock()
 		return fmt.Errorf("simulated miner %s is already running", m.Name)
 	}
 
@@ -118,7 +118,7 @@ func (m *SimulatedMiner) Start(config *Config) error {
 		fmt.Sprintf("[%s] Connecting to %s", time.Now().Format("15:04:05"), m.poolName),
 		fmt.Sprintf("[%s] Pool connected, algorithm: %s", time.Now().Format("15:04:05"), m.Algorithm),
 	}
-	m.mu.Unlock()
+	m.mutex.Unlock()
 
 	// Start background simulation
 	go m.runSimulation()
@@ -128,8 +128,8 @@ func (m *SimulatedMiner) Start(config *Config) error {
 
 // if err := miner.Stop(); err != nil { /* miner was not running */ }
 func (m *SimulatedMiner) Stop() error {
-	m.mu.Lock()
-	defer m.mu.Unlock()
+	m.mutex.Lock()
+	defer m.mutex.Unlock()
 
 	if !m.Running {
 		return fmt.Errorf("simulated miner %s is not running", m.Name)
@@ -164,8 +164,8 @@ func (m *SimulatedMiner) runSimulation() {
 }
 
 func (m *SimulatedMiner) updateHashrate() {
-	m.mu.Lock()
-	defer m.mu.Unlock()
+	m.mutex.Lock()
+	defer m.mutex.Unlock()
 
 	// Generate hashrate with variance and smooth transitions
 	now := time.Now()
@@ -243,8 +243,8 @@ func (m *SimulatedMiner) updateHashrate() {
 }
 
 func (m *SimulatedMiner) simulateShare() {
-	m.mu.Lock()
-	defer m.mu.Unlock()
+	m.mutex.Lock()
+	defer m.mutex.Unlock()
 
 	// 2% chance of rejected share
 	if rand.Float64() < 0.02 {
@@ -265,8 +265,8 @@ func (m *SimulatedMiner) simulateShare() {
 // metrics, err := miner.GetStats(ctx)
 // fmt.Printf("hashrate: %d H/s, shares: %d\n", metrics.Hashrate, metrics.Shares)
 func (m *SimulatedMiner) GetStats(ctx context.Context) (*PerformanceMetrics, error) {
-	m.mu.RLock()
-	defer m.mu.RUnlock()
+	m.mutex.RLock()
+	defer m.mutex.RUnlock()
 
 	if !m.Running {
 		return nil, fmt.Errorf("simulated miner %s is not running", m.Name)
@@ -335,8 +335,8 @@ func (m *SimulatedMiner) GetLatestVersion() (string, error) {
 
 // points := miner.GetHashrateHistory()  // snapshot of high-res window (last 5 min)
 func (m *SimulatedMiner) GetHashrateHistory() []HashratePoint {
-	m.mu.RLock()
-	defer m.mu.RUnlock()
+	m.mutex.RLock()
+	defer m.mutex.RUnlock()
 
 	result := make([]HashratePoint, len(m.HashrateHistory))
 	copy(result, m.HashrateHistory)
@@ -345,15 +345,15 @@ func (m *SimulatedMiner) GetHashrateHistory() []HashratePoint {
 
 // miner.AddHashratePoint(HashratePoint{Timestamp: now, Hashrate: 5000})
 func (m *SimulatedMiner) AddHashratePoint(point HashratePoint) {
-	m.mu.Lock()
-	defer m.mu.Unlock()
+	m.mutex.Lock()
+	defer m.mutex.Unlock()
 	m.HashrateHistory = append(m.HashrateHistory, point)
 }
 
 // manager.ReduceHashrateHistory(miner, time.Now())
 func (m *SimulatedMiner) ReduceHashrateHistory(now time.Time) {
-	m.mu.Lock()
-	defer m.mu.Unlock()
+	m.mutex.Lock()
+	defer m.mutex.Unlock()
 
 	// Move old high-res points to low-res
 	cutoff := now.Add(-HighResolutionDuration)
@@ -395,8 +395,8 @@ func (m *SimulatedMiner) ReduceHashrateHistory(now time.Time) {
 
 // logs := miner.GetLogs()  // capped at 100 lines, includes share accept/reject events
 func (m *SimulatedMiner) GetLogs() []string {
-	m.mu.RLock()
-	defer m.mu.RUnlock()
+	m.mutex.RLock()
+	defer m.mutex.RUnlock()
 
 	result := make([]string, len(m.logs))
 	copy(result, m.logs)
@@ -405,8 +405,8 @@ func (m *SimulatedMiner) GetLogs() []string {
 
 // if err := miner.WriteStdin("h"); err != nil { /* not running */ }
 func (m *SimulatedMiner) WriteStdin(input string) error {
-	m.mu.Lock()
-	defer m.mu.Unlock()
+	m.mutex.Lock()
+	defer m.mutex.Unlock()
 
 	if !m.Running {
 		return fmt.Errorf("simulated miner %s is not running", m.Name)