refactor(Worklets): two-step initialization

[tjzel]

Summary

Splitting initialization of WorkletsModuleProxy into two steps. Instead of WorkletsModule.installTurboModule() starting all the native pipeline, it only creates an instance of WorkletsModuleProxy which is later on properly fully initialized with WorkletsModule.start().

This is necessary for

• refactor(Worklets): load unpackers with JSI #8984

where WorkletsModuleProxy exposes bindings to register value unpackers code - thanks to that we don't have to pass the unpackers code from Kotlin/ObjC but have them exactly in C++ to use in Worklet Runtimes.

Test plan

Fabric Example runs both on iOS and Android

[Copilot]

Pull request overview

Refactors Worklets initialization into a two-step flow: installTurboModule() creates the WorkletsModuleProxy, and a new start() call completes native pipeline initialization (enabling C++-side runtime bindings/unpackers work per #8984).

Changes:

• Added a start() method to the Worklets TurboModule spec and implemented it across JS/Native (iOS/Android/C++).
• Moved UI-runtime initialization/runtime decoration work from WorkletsModuleProxy constructor into a new WorkletsModuleProxy::start().
• Adjusted JSI utility API (optimizedFromHostObject) and wiring to decorate the RN runtime proxy earlier.

Reviewed changes

Copilot reviewed 13 out of 14 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
packages/react-native-worklets/src/specs/NativeWorkletsModule.ts	Adds start() to the TurboModule TypeScript spec.
packages/react-native-worklets/src/WorkletsModule/NativeWorklets.native.ts	Calls start() after installTurboModule() and tightens RN-runtime detection.
packages/react-native-worklets/apple/worklets/apple/WorkletsModule.mm	Exposes start as a blocking synchronous method on iOS.
packages/react-native-worklets/android/src/no-networking/com/swmansion/worklets/WorkletsModule.kt	Adds synchronous start() and native startCpp() binding (no-networking flavor).
packages/react-native-worklets/android/src/networking/com/swmansion/worklets/WorkletsModule.kt	Adds synchronous start() and native startCpp() binding (networking flavor).
packages/react-native-worklets/android/src/main/cpp/worklets/android/WorkletsModule.h	Declares startCpp() in C++ hybrid module.
packages/react-native-worklets/android/src/main/cpp/worklets/android/WorkletsModule.cpp	Implements startCpp() and registers it with JNI.
packages/react-native-worklets/android/CMakeLists.txt	Minor target_link_libraries formatting/ordering tweak.
packages/react-native-worklets/Common/cpp/worklets/WorkletRuntime/WorkletRuntime.cpp	Removes an include no longer needed after refactor.
packages/react-native-worklets/Common/cpp/worklets/Tools/WorkletsJSIUtils.h	Changes optimizedFromHostObject signature to take const shared_ptr&.
packages/react-native-worklets/Common/cpp/worklets/Tools/WorkletsJSIUtils.cpp	Updates optimizedFromHostObject definition accordingly.
packages/react-native-worklets/Common/cpp/worklets/NativeModules/WorkletsModuleProxy.h	Adds start() and stores RN runtime proxy instance.
packages/react-native-worklets/Common/cpp/worklets/NativeModules/WorkletsModuleProxy.cpp	Moves UI runtime init/decorate logic into start(); decorates RN runtime in constructor.
apps/fabric-example/ios/Podfile.lock	Updates dependency checksums from running pod install.

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