fish-deps status now shows ⚠ with the current version when fish < 4.0.
fish-deps install prompts to upgrade fish when the installed version is
below 4.0, using the same install methods (cargo/PM) and printing a
restart reminder on success.
Installed deps show a green ✓. Missing required/integration deps show
a red ✗. Missing recommended deps show a yellow ⚠ since they are
optional, distinguishing severity at a glance.