Release InKraft v2.0.0

[SuperSandyman]

Summary

Prepare the InKraft v2.0.0 release.

This PR includes:

• dependency updates and CI verification for main
• CMS noindex protections
• hardened content write operations
• migration from NextAuth to Better Auth with legacy env compatibility
• refreshed CMS dashboard/sidebar/editor/list UI
• mobile editor improvements with collapsible metadata panels
• AI template generation provider selection for Google Vertex AI and OpenAI
• package version bump to 2.0.0
• README refresh for v2 setup, auth, deployment, and AI provider configuration

Impact

• Existing NextAuth sessions will not carry over to Better Auth, so users may need to sign in again after deployment.
• Production deployments should set a strong BETTER_AUTH_SECRET and a stable BETTER_AUTH_URL.
• AI template generation defaults to Google Vertex AI, with OpenAI available via AI_PROVIDER=openai.

Validation

• npx tsc --noEmit
• npm run lint
• npm test -- --run
• npm run build