refactor: modernize sync/atomic usage with typed atomic apis

[chuanshanjida]

Modernize sync/atomic usage with typed atomic APIs

Replace legacy sync/atomic function-based API (AddInt32, LoadInt32, etc.)
with Go 1.19+ typed atomic types (atomic.Int32, atomic.Int64, etc.).

This change:

• Improves code readability by removing explicit address-of operators
• Enhances type safety at compile-time
• Provides better API ergonomics with method-based access
• Aligns with modern Go best practices (More info sync/atomic: add typed atomic values golang/go#50860)

The transformation is source-compatible and requires Go 1.19 or later.

[chuanshanjida]

@JoeGruffins @buck54321 Hi, Could you please review this PR at your convenience? Thank you very much.