release(v0.2.0): generator emits a runnable Next.js scaffold for one instruction

[thopatevijay]

• Tag release and publish steps.

• Ensure README updated with examples.

Acceptance criteria

• npx @castui/cli --idl tests/fixtures/simple_idl.json --out ./tmp generates a runnable Next.js scaffold that yarn dev can start.

• Release notes are present and GitHub release created.