docs: Add documentation regarding HybridSDK target removal

[itaybre]

This decision documents the removal of the HybridSDK subspec and module, consolidating all hybrid APIs into the main Sentry target.

Background

Until v9.1.0, we maintained a separate SDK variant with additional public headers/APIs for downstream SDKs (React Native, Flutter, .NET, SwiftUI). This separation:

• Required maintaining multiple distribution variants
• Increased CI complexity and team workload
• Provided no real protection (users could still access "internal" APIs by switching dependencies)

Decision

Remove the HybridSDK submodule and subspec, treating hybrid SDK consumers as first-class citizens by:

• Exposing required APIs in a documented manner
• Avoiding breaking changes to these APIs in minor versions
• Using naming conventions to distinguish internal APIs from user-facing ones

Next Steps

1. Consolidate headers into the main target and remove HybridSDK subspec, done in chore: Removes HybridSDK subspec #7019
2. Update downstream SDKs
3. Align on an API naming convention (gather input from other SDK maintainers)

[buenaflor]

Hmm, I don't have a strong preference - as long as we can call it from hybrids I don't think it matters much to us. perhaps SentrySDK.internal.xyz?

I'd go for whatever the team feels more natural for cocoa

[philipphofmann]

I would not even mention it in the SentrySDK, because then it surfaces to our users, and it could confuse them. I would put it into an extra API. InternalSentrySDK. could work, or we could just keep PrivateSentrySDKOnly. Then it's easier for Hybrid to switch.

[itaybre]

Yeah, I would try to avoid using SentrySDK.

[buenaflor]

We've been using InternalSentrySdk for Android as well

might make sense to align here

[itaybre]

Indeed, seems like a good oportunity to align

[philipphofmann]

Thanks

[philipphofmann]

I would not even mention it in the SentrySDK, because then it surfaces to our users, and it could confuse them. I would put it into an extra API. InternalSentrySDK. could work, or we could just keep PrivateSentrySDKOnly. Then it's easier for Hybrid to switch.