Features for named lock monitoring and deadlock detection.

• ContextMutex<T> - Named mutex with timing tracking
• ContextRwLock<T> - Named read-write lock
• ContextSemaphore - Named semaphore with permit tracking

• Track who holds what locks and for how long
• Track who's waiting for locks and wait times
• Automatic deadlock risk detection
• Lock status in context tree display

// Create named locks within context
let user_lock = ctx.mutex("user-data-lock", UserData::new());

// Lock operations automatically tracked
let guard = user_lock.lock().await;
// Shows in status: "HOLDS user-data-lock (2.3s)"

// Waiting operations tracked
// Shows in status: "WAITING user-data-lock (5.1s) ⚠️ STUCK"

Implementation: After basic Context system + monitoring foundation.