replace provision hook with declarative apt_repos + vagrant_plugins (#1381)
Drop the arbitrary provision-script hook (and the content-hashing machinery) from the VM-profile schema, CLI, and Lima driver. Add declarative apt_repos (key + apt source line) and vagrant_plugins; the vergil-vm template owns the install. compose accumulates them; the fingerprint covers them directly (no file I/O). Removes the #1369 root-code-in-credentialed-VM seam for this feature. Tracks vergil-vm#105.