Allow for more explicit API declarations

[aleksandar-apostolov]

Goal

Allow for more explicit API declaration from within core.

Implementation

Enable explicit-api=struct
Add new annotation
@StreamPublishedApi
remove @StreamCoreApi
Add a new lint check for @StreamPublishedApi

In a nutshell a public api in the core.api package has to be either @StreamPublishedApi (safe to expose) or @StreamInternalApi (unsafe to expose) and even if exposed by accident still requires opt in from integration side.

[Copilot]

Pull Request Overview

This PR enables more explicit API declarations by implementing a structured approach to mark APIs as either safe to expose or internal-only. It introduces new annotation markers and a lint check to enforce proper API classification.

• Remove @StreamCoreApi annotation and replace with @StreamPublishedApi and @StreamInternalApi
• Enable explicit API mode in Kotlin compiler to require visibility modifiers
• Add lint detector to enforce API annotation requirements

Reviewed Changes

Copilot reviewed 47 out of 48 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
build.gradle.kts	Enable explicit API mode and update compiler opt-ins
StreamApiMarkers.kt	Replace @StreamCoreApi with @StreamPublishedApi annotation
StreamApiExplicitMarkerDetector.kt	New lint detector to enforce API annotation requirements
Multiple API files	Replace @StreamCoreApi with @StreamInternalApi/@StreamPublishedApi and add public modifiers
lint.xml	Update lint configuration for new API marker rule

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[gpunto]

Looks good, just a few doubts