[Feature Request] Multi-Regime Deployments Through Dynamic Prefixing

# Multi-Regime Deployments Request Through Dynamic Prefixing

By default, Stellar Engine **does not** support deploying environments for multiple compliance regimes (e.g., FedRAMP High and IL5) side-by-side using the same configured `prefix` within the same Google Cloud Organization.

## The Problem

When attempting to deploy multiple compliance regimes (like FedRAMP High and IL5) in the same organization using the same `prefix`, you will encounter naming collisions.

GCP Project IDs must be globally unique across all of Google Cloud. While you might assume Google Cloud will automatically append a random string to your Project Name to create a unique Project ID (which it does in the web console), Terraform and the Stellar Engine modules **explicitly define** the `project_id`.

For example, when creating the core automation project, the module explicitly tells GCP to name the ID exactly `[prefix]-prod-iac-core-0` (e.g... `stlr-prod-iac-core-0`). If you deploy FedRAMP High and then try to deploy IL5 using the same `prefix = "stlr"`, Terraform will attempt to create a project with the exact same ID. This will result in an immediate `409 Already Exists` error, blocking the deployment.

Unless the administrator manually creates distinct and totally separate `prefix` names for every compliance regime they wish to deploy, the default configuration inherently creates naming collisions.

## The Solution: Dynamic Regime Prefixing

To elegantly solve this limitation without forcing the administrator to invent disjoint configurations and manually track distinct prefixes per deployment, we implemented **Dynamic Regime Prefixing** into the codebase.

When you deploy a Stellar Engine environment, the Stage 0 bootstrap pulls your `prefix` defined in `terraform.tfvars` and automatically augments it using a short code corresponding to your chosen `assured_workloads.regime`.

For example, if your configuration defines:
```hcl
prefix = "stlr"
assured_workloads = {
regime = "IL5"
}
```

The bootstrap stage injects the `-il5` short code and computes the `effective_prefix` as `stlr-il5`. All core automation projects will then be dynamically named and assigned a unique Project ID (e.g., `stlr-il5-prod-iac-core-0` instead of a generic `stlr-prod-iac-core-0`).

This applies to all regimes defined in the `regime_mapping` variable. For example:
* **FedRAMP High:** Generates the suffix `-frh`.
* **FedRAMP Moderate:** Generates the suffix `-frm`.
* **Impact Level 4 (IL4):** Generates the suffix `-il4`.

This augmented prefix is exported as a global variable so that when you move to Stage 1, Stage 2, and Stage 3, the subsequent Terraform configurations automatically inherit the `stlr-il5` (or `stlr-frh`, etc.) prefix. This seamless injection completely eliminates naming collisions and allows you to spin up FedRAMP High, IL5, and other regimes synchronously in the same organization.