fix: race condition in AddToContext

[openclaw-for-ben]

Problem

The AddToContext function mutated a shared map stored in the context. When multiple goroutines called AddToContext on contexts derived from the same parent, they would corrupt each other's data.

// Old implementation - race condition!
data, ok := v.(map[string]any)
if ok {
    mutex.Lock()
    data[key] = value  // mutating shared map
    mutex.Unlock()
}
return ctx  // returning original context with mutated map

The mutex only protected the write operation, but the map itself was shared across all derived contexts.

Solution

Create a new map for each call, copying existing data:

func AddToContext(ctx context.Context, key string, value any) context.Context {
    newData := map[string]any{key: value}
    if v := ctx.Value(dataCtxKey); v != nil {
        if data, ok := v.(map[string]any); ok {
            for k, v := range data {
                newData[k] = v
            }
        }
    }
    return context.WithValue(ctx, dataCtxKey, newData)
}

This ensures no shared mutable state. The global mutex has been removed as it's no longer needed.