Add waitLeave and isLocked methods

[knowledgecode]

Summary

• Add waitLeave() method: waits for critical section release without locking it
• Add isLocked() method: checks if object is currently locked
• Refactor internal implementation with improved code structure
• Add comprehensive test coverage for new methods
• Update documentation with new API references and usage examples

Changes

Core Implementation

• Add waitLeave(obj, timeout): waits for release without acquiring lock
• Add isLocked(obj): non-destructive lock status check
• Rename Occupation interface to Locking for clarity
• Rename _occupy() to _lock() for consistency
• Extract _wait() method to reduce code duplication
• Update all type guards from isOccupation to isLocking

Testing

• Add 5 test cases for waitLeave() covering timeout, non-locking behavior
• Add 4 test cases for isLocked() covering various lock states
• Update terminology from "unoccupied" to "unlocked" in test comments

Documentation

• Add API documentation for waitLeave() and isLocked()
• Add "Monitoring Resource Availability" usage pattern section
• Update method count from 3 to 5 in Key Features
• Update terminology from "occupied" to "locked" throughout

Test plan

• All existing tests pass
• New tests cover waitLeave() behavior (immediate return, waiting, timeout)
• New tests cover isLocked() behavior (locked/unlocked states, independence)
• Documentation examples are accurate and clear