feat: Add fullstack Docusaurus CloudFront template

[fshmng09]

Summary

Add a comprehensive fullstack template for deploying Docusaurus documentation sites to AWS CloudFront with flexible authentication options.

Changes

Infrastructure (Terraform)

• Modular Terraform structure (infra/modules/docusaurus + infra/environments/dev)
• Support 4 authentication types:
  • None: Public access
  • Basic: CloudFront Functions
  • Cognito: Lambda@Edge + OAuth2
  • IP Restriction: AWS WAF
• Automated file organization by resource type (S3, CloudFront, Cognito, WAF, IAM)
• GitHub Actions OIDC authentication for deployment

Docusaurus Application

• Modern Docusaurus v3.9.1 setup
• TypeScript configuration
• Custom CSS and homepage template
• Ready-to-use documentation structure

Version Management

• mise configuration for Terraform 1.9.8 and Node.js 20.18.0
• mise tasks for common operations
• Consistent development environment across team

CI/CD

• GitHub Actions workflow for automated deployment
• S3 sync with optimized cache headers
• CloudFront invalidation

Documentation

• Comprehensive README.md with setup instructions
• MISE.md for version management guide
• Authentication configuration examples
• Cost estimation guide

Architecture

User -> Route53 -> CloudFront -> [Authentication] -> S3 (Docusaurus)
                                      |
                                      +-> Basic: CloudFront Functions
                                      +-> Cognito: Lambda@Edge
                                      +-> IP: AWS WAF

Cost Estimation

• Base: $2.00/month (S3 + CloudFront + Route53)
• Auth: $0 - $6.00/month (depending on authentication type)

Testing

• Terraform validate passes
• Docusaurus builds successfully
• mise configuration works
• GitHub Actions workflow syntax is valid