Update the Russian translation of the app

[kytta]

Back when I did the Russian translation, I did it quite hastily, and now have discovered some mistakes. I have also fixed some mistakes other Russian translators may have done.

Don't fear the abundance of commits — I have decided to break them apart for each individual type of change for a better description of it and an easier rollback, if necessary :) You can squash the commits when merging this I can do it for you and overwrite the already pushed commits, no biggie

Things changed in this PR:

• some strings had a Cyrillic version of the name "Keka" — made sure the English one is used everywhere
• shortened lots of strings
  • this way they're easier to read
  • this also compensates the fact that Russian words can be very long
• translated strings that were left untranslated
• fixed punctuation and orthography errors
• updated my website (since I have a new domain now)

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P.S. I just noticed that Oleg had opened a similar PR (#644); it's similar to what I did, just to a lesser extent and also with some questionable punctuation (no offence whatsoever). Idk how to resolve both of the PRs without causing git conflicts and translation inconsistency 🤔

[aonez]

I'm merging this one first since it came before. Will check then with @Oleg-Chashko :)

[aonez]

• some strings had a Cyrillic version of the name "Keka"

By the way thanks for that one and cool new domain 😉