Remove obsolete artifacts and update Nomad deployment documentation

[ExtraToast]

This pull request updates the infrastructure documentation, repository structure, and configuration to migrate from Docker Swarm to HashiCorp Nomad (with Consul for service discovery) as the orchestration platform. It also updates secrets management to use Nomad workload identity integration with Vault, and adapts CI/CD, monitoring, and testing strategies accordingly. The changes are reflected across architecture docs, ADRs, README files, and directory structure documentation.

Infrastructure orchestration migration:

• Replaces references to Docker Swarm with Nomad (plus Consul for service discovery) throughout architecture docs, ADRs, and the main README, including updating the orchestration layer, network communication, and deployment strategies. [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16]

• Updates repository structure documentation and directory listings to add a new infra/nomad/ directory for Nomad jobs/templates and Vault roles, and removes/updates Swarm-related files and descriptions. [1] [2] [3] [4]

Secrets management improvements:

• Switches Vault service authentication from AppRole to Nomad workload identity, removing the need for static secret distribution and updating ADRs and documentation to reflect this change. [1] [2] [3] [4] [5]

CI/CD and deployment process updates:

• Changes CI/CD pipeline documentation to describe deploying with Nomad using infra/scripts/deploy.sh and per-job rolling updates, replacing Swarm stack deploys and atomic updates. [1] [2] [3] [4] [5] [6]

Monitoring, testing, and automation adjustments:

• Updates monitoring, system testing, and automation ADRs to use Nomad-based deployments and service discovery, removing Swarm-specific details. [1] [2] [3] [4] [5]

Minor cleanups:

• Removes Swarm-specific files from workflow and documentation, such as docker-compose.prod.yml. [1] [2]

These changes collectively modernize the stack's orchestration, secrets management, and operational practices, aligning documentation and structure with the new Nomad-based approach.