fix: High memory usage, Bound hook dispatch backlogs

[boralp]

This is a fix for Issue #150

Root cause:
Long-running memory growth came from dispatch backlog risk in hook event pipelines. Producer callbacks can outpace consumer dispatch temporarily (gesture/scroll bursts, scheduling stalls, reconnect periods), and without a hard queue bound this can accumulate unbounded event objects over time.

What changed:

• Added shared dispatch queue management in BaseMouseHook:
  • _dispatch_queue attribute
  • _init_dispatch_queue(maxsize)
  • _enqueue_dispatch_event(event) with best-effort behavior:
    • non-blocking enqueue
    • if full: drop oldest, retry once
    • if still full: drop new event and emit debug message
• Updated platform hooks to use shared bounded queue init:
  • macOS: _init_dispatch_queue(maxsize=512)
  • Windows: _init_dispatch_queue(maxsize=512)
• Updated event producer paths to use _enqueue_dispatch_event(...) rather
  than direct queue puts.
• Added unit tests for queue overflow semantics:
  • verifies bounded capacity with oldest-drop behavior
  • verifies debug emission when queue remains saturated

Why:
This makes memory usage stable under transient overload and keeps recent input intent prioritized over stale backlog replay, improving long-run correctness and resilience.