fix: make sure native libs are loaded for RN >= 0.80

[marcinszalski-callstack]

Summary

loadNativeLibs() in ReactNativeBrownfield.kt is a no-op for RN >= 0.80. All ReactNativeHostManager templates call loadReactNative(application) BEFORE ReactNativeBrownfield.initialize(), so when done through the recommended path the libs load. But loadNativeLibs() — called inside every initialize() overload — silently skips for RN >= 0.80. Any consumer using ReactNativeBrownfield.initialize() directly — with a custom ReactHost, custom packages list, or custom options — skipped native lib loading entirely. Without JNI_OnLoad firing, registerComponentDescriptorsFromEntryPoint and the DefaultTurboModuleManagerDelegate module providers were never assigned, leading to the SIGSEGV during Fabric initialization.

ddc011c — moved SoLoader.init() from preloadReactNative() into initialize(application, rnHost, ...). Before this, SoLoader.init() was called inside preloadReactNative after creating the React context. It was consolidated into the initialize entry point.
9908b68 — added the RN_THRESHOLD_VERSION = "0.80.0" gate and removed SoLoader.init() + load() for RN ≥ 0.80, leaving those calls only for < 0.80.

ReactNativeBrownfield.initialize() itself had no fallback for the RN ≥ 0.80 case. If anything bypasses ReactNativeHostManager — a custom ReactHost, a consumer calling initialize() directly, or the generated ReactNativeApplicationEntryPoint being unavailable — native libs are never loaded. That's the bug this fix addresses.

Test plan

To genuinely reproduce the original crash we'd need one of:

• the version of the AAR from before 59f472b consumed by the reporter's enterprise app
• an APK that deliberately ships two conflicting versions of libreact_codegen_rnscreens.so

Neither is practical to set up cleanly. The SoLoader.init() not yet called crash the GH issue reporter produced is sufficient proof that the same class of bug exists — the fix prevents both the Java exception AND the conditions that led to the original native crash.

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Closes #283

[hurali97]

If I understand correctly, the crash happens because the user does not call the loadReactNative in some integrations, so we are saying that we will do it for them if they do not follow the docs?

Since we are now using Reflection, we will need to ask the User to add this ReactNativeApplicationEntryPoint to their consumer-rules - so this is one extra step for them and we need to document it, see here

Also, let's get rid of RN <=80 support, only keep 80+ changes.

[artus9033]

LGTM after 1 comment, great job!

[artus9033]

LGTM, seems like OpenSourceMergedSoMapping is present for RN since 0.77 (ref) so IMO we're good to go with this. I like the new flattened logic.