refactor: simplify template storage and runtime tests

[homelab-agent-bot]

Summary

• move Supervisor service-command integration coverage from image CI into the template runtime test
• replace the broad test-mode switch with explicit kubeconfig and dotfiles-script controls
• mount the template ConfigMap once at /scripts and update every consumer
• expose mutable home and temporary PVC sizes, with tmp constrained to 1-50 GiB and defaulting to 1 GiB

Runtime contract

Area	Assertion
Parameters	Coder's published metadata reports mutable home/tmp sizes and their exact bounds/defaults
Scripts	Every ConfigMap-backed executable and Supervisor configuration exists under /scripts
Services	Commands start after dotfiles, one restarts, and another remains independently running
Home	Data survives stop/start and a template-owned claim is deleted with the workspace
Tmp	The Pod-owned claim is deleted on stop and a distinct 2 GiB bound claim is provisioned on restart

The disposable Kind provisioner cannot validate in-place expansion of the persistent home volume. The test therefore
checks home mutability through Coder's rendered parameter contract while retaining the existing persistence and
deletion lifecycle assertions. Temporary storage is reprovisioned, so its requested and bound capacity are checked
against the live replacement PVC.

Validation

• pre-commit run --all-files
• tofu fmt -recursive -check
• tofu validate
• tflint --config=../../../.tflint.hcl
• independent code review, with both non-vacuity findings fixed