Optimize LoomManager async scheduling path - #7

Motivation

• Reduce allocations and improve stability in LoomManager's async scheduling and delayed-invocation loops while keeping the overall structure unchanged.
• Avoid potential race conditions when producers enqueue async actions while the main thread consumes them.

Description

• Introduce named constants ThreadPoolMaxWorkerThreads and ThreadPoolMinWorkerThreads and use them in Initialize to replace magic numbers.
• Cache a WaitCallback in the readonly field _runActionCallback (assigned in the new constructor) and use it instead of allocating new WaitCallback(RunAction) on each dispatch.
• Add locking around _waitingAsyncActions for safe enqueue/dequeue and change Update to dequeue a single waiting action under lock then schedule it, preventing double-dequeue and races.
• Cache Time.unscaledTime and Time.frameCount at the start of Update and use the cached values inside the delay loops to reduce repeated Unity API calls.

Testing

• No automated Unity build or runtime tests were executed in this environment.
• The patch was applied and the modified file was inspected and verified for expected diffs and basic consistency within the repository environment.

Codex Task