Explosion in a Moscow restaurant: what is known about General Chayko?

Consensus

The explosion occurred on August 1 at the Balzi Rossi restaurant on Kudrinskaya Plaza in Moscow.
The explosion was caused by a homemade explosive device.
Three people initially reported dead, later confirmed to be five, including the courier, an officer, and a visitor.
Twenty-one people were injured in the blast.
The National Anti-Terrorist Committee (NAK) confirmed the incident was a terrorist act.
The Moscow City Hall and law enforcement agencies are investigating the incident.
The investigation is ongoing, with authorities working to identify the courier and determine the motive.
The restaurant was hosting a private event at the time of the explosion.
The area around the building was cordoned off, and emergency services responded immediately.
The Moscow Mayor, Sergey Sobyanin, referred to the event as a 'brutal terrorist act' and pledged that perpetrators would be punished.

The attack was likely aimed at General Alexander Chayko, who was allegedly celebrating his 55th birthday at the event, and that high-ranking FSB officials, generals, and politicians attended. — tg_dwglavnoe
The attack was likely aimed at General Alexander Chayко, who was the intended target, and that he was not injured. — meduza
The bomb was detonated remotely, and the courier likely did not know about the explosive content. — fontanka
The number of fatalities increased to five, with two additional deaths reported later in the hospital. — vedomosti
The event was a private celebration, and the attack targeted the guests at the venue. — mn
The courier was carrying a 'gift' for the guests, and the bomb was detonated during a search by the security guard. — vesti