Simplify: centralize paths in layout, dedup zfs snapshot refs, remove dead code

- Add layout.Config methods (ReleasesDir, PostReceiveHookPath, RCScriptPath,
  RCConfPath) so main.go and jailmgr no longer hand-build paths that layout
  already owns.
- Extract zfsutil.snapRef to replace three inline dataset@tag Sprintfs.
- Remove seven unused exported functions (zfsutil.Exists, jailmgr.Stop,
  sh.RunWithStdinFile, and four dead layout.Config path methods) and their
  now-unused imports.

1 files changed, 2 insertions, 4 deletions

diff --git a/cmd/skiff/main.go b/cmd/skiff/main.go
index e709227..33aaf5e 100644
--- a/cmd/skiff/main.go
+++ b/cmd/skiff/main.go
@@ -7,7 +7,6 @@ import (
 	"flag"
 	"fmt"
 	"os"
-	"path/filepath"
 	"strings"
 
 	"skiff/internal/appmeta"
@@ -90,7 +89,7 @@ func cmdNewApp(args []string) error {
 		return fmt.Errorf("clone base dataset: %w", err)
 	}
 
-	if err := os.MkdirAll(filepath.Join(cfg.AppDir(*name), "releases"), 0755); err != nil {
+	if err := os.MkdirAll(cfg.ReleasesDir(*name), 0755); err != nil {
 		return fmt.Errorf("create app dir: %w", err)
 	}
 
@@ -115,8 +114,7 @@ func cmdNewApp(args []string) error {
 	if err != nil {
 		return err
 	}
-	hookPath := filepath.Join(cfg.RepoPath(*name), "hooks", "post-receive")
-	if err := os.WriteFile(hookPath, []byte(hook), 0755); err != nil {
+	if err := os.WriteFile(cfg.PostReceiveHookPath(*name), []byte(hook), 0755); err != nil {
 		return fmt.Errorf("install post-receive hook: %w", err)
 	}