feat: add workspace selection (#35)

## what
- Update the terraform plan/apply/refresh to select a workspace

## why
- This is the pattern we use for clients and have setup in mp-infra

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

* **Chores**
* Enhanced Terraform deployment pipeline by adding automatic workspace
initialization. Plan, apply, and refresh operations now automatically
verify and create required workspaces for target environments before
execution. This streamlines the deployment process and reduces manual
setup requirements while preserving existing validation checks.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Author: westonplatter

lib/terraform/Taskfile.yml

@@ -16,14 +16,14 @@ tasks:
     silent: true
     internal: true
     vars: &vars
-      ENV:
+      WORKSPACE:
         sh: echo "{{.CLI_ARGS}}" | cut -d ' ' -f1 | xargs
       TF_ARGS:
         sh: echo "{{.CLI_ARGS}}" | cut -s -d ' ' -f2- | xargs
       BACKEND_CONFIG_FILE:
-        sh: echo "{{.BACKEND_CONFIG_PATH}}/{{.ENV}}.backend.tf"
+        sh: echo "{{.BACKEND_CONFIG_PATH}}/{{.WORKSPACE}}.backend.tf"
       TFVARS_FILE:
-        sh: echo "{{.TFVARS_PATH}}/{{.ENV}}.tfvars"
+        sh: echo "{{.TFVARS_PATH}}/{{.WORKSPACE}}.tfvars"
 
   init:
     desc: Initialize Terraform working directory with a backend configuration file.
@@ -56,6 +56,7 @@ tasks:
       - sh: test -f {{.TFVARS_FILE}}
         msg: "Variables file does not exist: {{.TFVARS_FILE}}"
     cmds:
+      - terraform workspace select -or-create {{.WORKSPACE}}
       - terraform plan -var-file {{.TFVARS_FILE}} {{.TF_ARGS}}
 
   apply:
@@ -73,6 +74,7 @@ tasks:
       - sh: test -f {{.TFVARS_FILE}}
         msg: "Variables file does not exist: {{.TFVARS_FILE}}"
     cmds:
+      - terraform workspace select -or-create {{.WORKSPACE}}
       - terraform apply -var-file {{.TFVARS_FILE}} {{.TF_ARGS}}
 
   refresh:
@@ -90,4 +92,5 @@ tasks:
       - sh: test -f {{.TFVARS_FILE}}
         msg: "Variables file does not exist: {{.TFVARS_FILE}}"
     cmds:
+      - terraform workspace select -or-create {{.WORKSPACE}}
       - terraform apply -refresh-only -var-file {{.TFVARS_FILE}} {{.TF_ARGS}}