Maintenance: detect dead code on CI via periphery

[nikitabobko]

https://github.com/peripheryapp/periphery

diagnostics can be ignored via:

// periphery:ignore
class MyClass {}

// periphery:ignore:parameters unusedOne,unusedTwo
func someFunc(used: String, unusedOne: String, unusedTwo: String) {
    print(used)
}

https://github.com/peripheryapp/periphery?tab=readme-ov-file#comment-commands

[nikitabobko]

Done in main