fix: race condition in resetLogLevel

[openclaw-for-ben]

Problem

Two issues in logLevelSetter:

1. Data race in resetLogLevel()

func (l *logLevelSetter) Set(...) {
    l.mux.Lock()
    l.lastSetTime = time.Now()  // writes with lock
    l.mux.Unlock()
    go func() {
        <-ctx.Done()
        l.resetLogLevel()
    }()
}

func (l *logLevelSetter) resetLogLevel() {
    if time.Since(l.lastSetTime) <= l.autoResetDuration {  // reads WITHOUT lock!
        ...
    }
}

2. Context cancellation triggers early reset

The reset goroutine inherited the caller's context, so if an HTTP request finished early, the log level would reset prematurely.

Solution

1. Add l.mux.Lock() to resetLogLevel()
2. Use context.Background() for the reset timer
3. Added concurrent access test (run with -race flag)