refactor(agents): replace invoke constructors with factory methods

[antoniibelyshev]

Replaced the pattern

class A {
    companion object {
        operator fun invoke(...) = /* create an instance of A */
    }
}

with

class A { ... }
fun A(...) = /* create an instance of A */

the usage does not change:

import x.y.z.A

val a = A()

but the resolution is clearer with the updated factories.

updated classes:
AIAgent, AIAgentService, ToolRegistry, RollbackToolRegistry, AIAgentPlannerStrategy.

BREAKING:
The unintended usage will break, e.g. these would compile previously, but will not compile now

A.Companion.invoke()
A.invoke()
A.Companion()
etc.

now only A(...) will be allowed.

[devcrocod]

Good PR 👍
left a few comments

[devcrocod]

Did you intentionally remove these operators without deprecating them?

[antoniibelyshev]

There is only a minor break in API, related to unintended uses of explicit invoke or Companion, so I decided not to keep deprecations here.

[devcrocod]

I'm not sure I fully understand about minor break
invoke operator is imported, so removing it would introduce source incompatibility for all users

[antoniibelyshev]

I did not think about this, I'll keep them as deprecated then

[devcrocod]

some specific logic in build?
I think you can take tools without calling build?

[antoniibelyshev]

Actually, builder.tools is private and not defined in the commonMain, so let's keep the build() here, as it was here before the refactoring

[devcrocod]

How would this look from Java?
Maybe it would be worth adding @JvmName

[antoniibelyshev]

These factories were not intended for use from java anyway (they were not marked @JvmStatic). Also, they are very inconvenient in java. So I think we should keep it this way and only expose AIAgent.builder for java