Adding volume and buttons and updating the Russian translation

[r57zone]

Hi, I've added volume control and buttons, and updated the Russian translation.

On many Android phones, the minimum volume setting doesn’t work well - it jumps by 5%, which can make podcasts, recordings, and audiobooks too loud for listening before bed. This update helps slightly adjust the volume for more comfortable listening in quiet environments.

Thank you for your amazing app and all your hard work!

[flackbash]

Thank you for the contribution!
I like having the volume adjustable within the app, however, I don't like the look of the controls so much and I'd rather not have the controls in the PlayActivity to begin with. I would prefer another element in the menu (could be placed before the sleep timer) that opens a dialog which allows the user to adjust the volume. This could look similar to the Playback speed dialog.

[r57zone]

Thanks for the feedback!

It seems that for users with many different recordings or podcasts (not audiobooks), volume levels can vary quite a bit, and having the controls directly on the PlayActivity might make quick adjustments easier. This approach is also fairly common in podcast players (for example, older versions of Apple Podcasts).

Perhaps, to avoid cluttering the UI, this could be toggled on or off in the settings.

Please feel free to reuse any of the changes if they're helpful.