WIP:Enhance CI/CD workflows and deployment configurations for TalentStreamAI

[haastrupea]

This pull request implements a working CI/CD pipeline and deployment workflow for the project, transitioning from placeholder scripts to real automation for both frontend and backend, as well as infrastructure provisioning. It also introduces Lambda compatibility for the backend, updates documentation to reflect the new deployment process, and tightens AWS OIDC trust policy for secure GitHub Actions integration.

CI/CD and Deployment Automation

• Replaces scaffolded GitHub Actions workflows with real jobs: ci.yml now runs frontend lint/build, backend Lambda packaging, and Terraform validation; deploy-aws.yml supports manual deploys (frontend, backend, OIDC, or all) with environment/target selection, OIDC credential bootstrapping, and invokes repository Python deploy scripts for full-stack automation. [1] [2] [3]
• Adds required repository/environment variables for deployment and documents them in the README. [1] [2]

Backend Lambda Compatibility

• Adds a lambda_handler.py using Mangum to expose FastAPI as an AWS Lambda handler, and includes mangum in both pyproject.toml and Lambda requirements. [1] [2] [3]
• Updates backend configuration with app_secrets_arns and helper property for secret ARNs.

Infrastructure and AWS Integration

• Refines the example AWS OIDC trust policy to restrict access to pushes to main and tags only, improving security.

Documentation Updates

• Overhauls the README.md to describe the new Terraform stack, deployment scripts, Lambda integration, and CI/CD workflows, including a new troubleshooting section and updated project structure. [1] [2] [3] [4] [5]

These changes collectively enable end-to-end automated deployment and infrastructure management for the project, with clear documentation and improved security practices.

[haastrupea]

it is ready to merge