fix: use PM_API_TOKEN_ID/SECRET env vars directly

- Remove token from Terraform variables (provider reads from env)
- Update workflows to set PM_API_TOKEN_ID and PM_API_TOKEN_SECRET directly
- Provider now reads credentials from environment variables

terraform/terraform.tfvars

@@ -1,10 +1,9 @@
-target_node     = "flex"
-clone_template  = "ubuntu-cloudinit"
-cores           = 1
-memory          = 1024
-disk_size       = "15G"
-sockets         = 1
-bridge          = "vmbr0"
-storage         = "Flash"
-pm_api_url      = "https://100.105.0.115:8006/api2/json"
-pm_api_token_id = "terraform-prov@pve!mytoken"
+target_node    = "flex"
+clone_template = "ubuntu-cloudinit"
+cores          = 1
+memory         = 1024
+disk_size      = "15G"
+sockets        = 1
+bridge         = "vmbr0"
+storage        = "Flash"
+pm_api_url     = "https://100.105.0.115:8006/api2/json"