[0.82]: Regressions tests after legacy code cleanup #15530

With Integration of last chunk of 0.82 RN code, we have removed significant legacy code, this issue tracks the test plan for fabric after removing the same.

ref : #15517

Threading & Message Queue Vineeth (@vineethkuttan)

Removed: BatchingQueueThread, BatchingMessageQueueThread

• App launches without thread-related crashes
• JS execution runs on dedicated JS thread
• Native-to-JS calls complete successfully
• Timers (setTimeout, setInterval) fire correctly
• Async operations (fetch, storage) complete

Debugger & Inspector Abhijeet Jha (@iamAbhi-916)

Affected: Threading changes, dev infrastructure

• RN DevTools connects via metro(8081)
• Breakpoints pause JS execution
• Console.log output appears in debugger
• Step through/over/into works
• Variables inspectable in scope
• React DevTools connects and shows component tree

Dev Server & Hot Reload Abhijeet Jha (@iamAbhi-916) Nitin Chaudhary (@Nitin-100)

Affected: OInstance.cpp, DevSettings.h changes

• Metro bundler connection established
• Initial bundle loads from dev server
• Fast Refresh triggers on file save
• Error overlay (RedBox) shows on JS errors
• Dev menu opens (Ctrl+Shift+D or shake)
• Reload option works from dev menu

TurboModules Protik Biswas (@protikbiswas100) Abhijeet Jha (@iamAbhi-916)

Removed: NativeModulesProvider, ABICxxModule, legacy module system

• TurboModule methods callable from JS
• Sync methods return values correctly
• Async methods resolve promises
• Callbacks invoked from native
• Events emitted to JS listeners
• Module constants accessible

Fabric Rendering Harini Malothu (@HariniMalothu17)

Indirect: Threading affects UI updates

• Components render on screen
• Layout calculated correctly
• Touch events handled
• Scroll views scroll smoothly
• State updates reflect in UI

Bundle Loading Abhijeet Jha (@iamAbhi-916)

Affected: OInstance.cpp changes

• Debug: Loads bundle from Metro
• Release: Loads embedded bundle
• Bundle parse errors show in RedBox
• Source maps work for stack traces

Build Verification Abhijeet Jha (@iamAbhi-916)

• x64 Debug builds clean
• x64 Release builds clean
• ARM64 Debug builds clean
• ARM64EC Release builds clean
• No unresolved symbol linker errors
• No C4996 warnings from RNW code (upstream RN OK)