Remove old architecture support after RN 0.87 update

[NicooleT]

Summary

• Removed Android Paper/old-architecture implementations, generated compatibility classes, architecture flags, and conditional source sets.
• Enabled the React Native Gradle plugin and TurboModule metadata unconditionally.
• Preserved Android React view props and moved required Fabric helpers into the main source set.
• Updated Android event dispatching to the RN 0.87 API.
• Removed legacy iOS views, managers, shadow views, local data, events, and the obsolete Xcode project.
• Made the iOS Fabric components, C++ shadow nodes, and TurboModule implementation unconditional.
• Removed old/new architecture switches from example projects, CI scripts, and the bug-report template.
• Updated the pod lockfile for the New Architecture-only configuration.
• Modernize new arch from fix: replace deep RN imports with public API #744