electron 持续获取程序运行时间

受chrome机制影响，熄屏、最小化等条件下会降低 setInterval 的频率，聚焦后恢复正常。所以获取程序运行时间应换一种方式实现，获取电脑开机时间，分别记录程序启动时间和当前开机时间，然后相减可得程序当前运行时间。

// 运行时间定时器
handleCheckUptime({ state, commit }) {
    const os = require('os');
    commit('SET_UPTIME_TIMER', { start: os.uptime() });
    clearInterval(state.game_running.check_uptime_timer);
    let timer = setInterval(() => {
        let diff = state.game_running.end - state.game_running.start;
        if (diff < 0) { diff = 0 }
        commit('SET_UPTIME_TIMER', { end: os.uptime(), diff });
        console.log('[ uptime ] >', state.game_running.start, state.game_running.end, state.game_running.diff);
    }, 1000);
    commit('SET_UPTIME_TIMER', { check_uptime_timer: timer })
}