Migrate SDK to latest/ directory structure with v2.0.0-rc.1 pre-release

[Gvieve]

Overview

This PR implements the next phase of the multi-version SDK support by migrating the SDK to a latest/ directory structure and configuring pre-release publishing for v2.0.0-rc.1.

Changes

• New files: Created retroactive CHANGELOG.md and MIGRATION.md guide at repository root
• Workflows: Updated generate.yml, generate_publish_release.yml, publish.yml, release.yml, and on-push-master.yml to support the new directory structure
• Output directory: SDK now generates to ./latest/ instead of root, so SDK generated files were removed from root
• Documentation bundling: LICENSE, CHANGELOG.md, and MIGRATION.md are copied to each version directory during generation
• Publishing: Added --tag next flag to publish as pre-release, allowing consumers to opt-in with npm install mx-platform-node@next
• Version reading: Release workflow now reads version directly from ./latest/package.json using jq (scalable for Phase 4 multi-version support)
• Trigger paths: Updated on-push-master.yml to only trigger on changes to latest/**, preventing unintended publishes from documentation or workflow changes

Version

• npmVersion: 2.0.0-rc.1 (pre-release for testing new structure)

Testing Required

• Merge to master should trigger publish with @next tag
• Consumers should be able to install with: npm install mx-platform-node@next
• Path-based triggers verified in Phase 1
• Package integrity and exports validation pending

[briangadoury]

"LGTM!"