Release docs alignment for v0.9.0 (README + CHANGELOG + VERSION)

[Copilot]

This updates release-facing documentation and metadata to reflect the v0.9.0 milestone. It also refreshes the README so it clearly communicates the current Coderive platform scope.

• Release metadata

  • Bumped root VERSION from 0.8.4 to 0.9.0.

• Changelog

  • Added a new top entry: v0.9.0 - Platform Snapshot - April 13, 2026.
  • Captured the release-level changes: version bump, README refresh, and metadata alignment.

• README refresh

  • Updated the version badge to 0.9.0.
  • Added a new “What Coderive offers today” section.
  • Expanded coverage of current offerings across language design, lazy data model, safety/execution model, runtime pipeline, CLI/project workflows, and docs/playground.
  • Added the new section to the Table of Contents.

## What Coderive offers today
- Expressive core language design
- High-scale lazy data model
- Safe + explicit execution model
- Bytecode and runtime pipeline
- CLI and project workflows
- Documentation and browser experience