refactor(nosql): fix critical issues in write-back system

[Claude]

Addresses critical bugs and performance issues in the write-back worker implementation that could cause panics, monitoring blindness, and slow shutdowns.

Changes

• Prevent nil panic in marshalAnyMap: Added nil check before reflect.TypeOf() to handle maps containing nil values safely

• Implement functional metrics: Replaced stub metrics with atomic counters tracking processed/failed operations, latency, and timestamps. Previously returned hardcoded zeros.

• Add database operation timeout: 30-second context timeout prevents indefinite hangs on slow database operations

• Fix duplicate logging: Removed redundant debug log statement in write-back handler

• Concurrent worker shutdown: Parallel worker stopping reduces shutdown time from O(N×5s) to O(5s) for N workers

• Standardize Chinese comments: Converted Traditional Chinese to Simplified Chinese throughout for consistency

Example: Metrics Before/After

// Before: Always returns zeros
func (w *WriteBackWorker) GetMetrics() WriteBackMetrics {
    return WriteBackMetrics{
        ProcessedCount: 0, // TODO: implement
        FailedCount:    0,
        AverageLatency: 0,
    }
}

// After: Real atomic metrics
func (w *WriteBackWorker) GetMetrics() WriteBackMetrics {
    processed := w.processedCount.Load()
    failed := w.failedCount.Load()
    avgLatency := time.Duration(w.totalLatency.Load() / processed)
    return WriteBackMetrics{
        ProcessedCount: processed,
        FailedCount:    failed,
        AverageLatency: avgLatency,
    }
}

[Copilot]

Pull request overview

This PR refactors the NoSQL write-back subsystem to improve safety, observability, and shutdown behavior in the asynchronous write-back worker/manager.

Changes:

• Added atomic, real metrics tracking to WriteBackWorker and exposed them via GetMetrics().
• Added a per-operation DB context timeout and removed duplicate success logging in the write-back handler.
• Improved manager shutdown latency by stopping workers concurrently; added a markdown summary of review fixes.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 5 comments.

File	Description
orm/nosql/worker.go	Adds atomic metrics, DB operation timeout, and removes duplicate success logging
orm/nosql/manager.go	Converts comments to简体中文 and stops workers concurrently; aggregates worker metrics
orm/nosql/common.go	Adds nil-value handling to marshalAnyMap to prevent reflect.TypeOf(nil) panic
CODE_REVIEW_FIXES.md	Documents the applied review fixes and expected impact

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