refactor: restructure repo into environments/modules layout

Separates nonprod into its own working directory for independent
state isolation. Follows HashiCorp guidance on environment separation.

environments/nonprod/main.tf

@@ -0,0 +1,18 @@
+terraform {
+  required_version = ">= 1.0"
+
+  required_providers {
+    proxmox = {
+      source  = "bpg/proxmox"
+      version = "~> 0.73"
+    }
+  }
+}
+
+provider "proxmox" {
+  endpoint = var.proxmox_endpoint
+  api_token = var.proxmox_api_token
+
+  # Set to true if using a self-signed certificate (common on home labs)
+  insecure = var.proxmox_insecure
+}