refactor: simplify path policy and TUI reducers

internal/shell/shell.go

@@ -14,6 +14,7 @@ import (
 	"path/filepath"
 	"strings"
 
+	"proxyctl/internal/pathutil"
 	"proxyctl/internal/profile"
 	"proxyctl/internal/securefs"
 	"proxyctl/internal/target"
@@ -84,24 +85,7 @@ func ResolveConfiguration(environment profile.IdentityEnvironment) (Configuratio
 	}, nil
 }
 
-func ResolveConfigurationForCurrentProcess() (Configuration, error) {
-	return ResolveConfiguration(systemEnvironment{})
-}
-
-type systemEnvironment struct{}
-
-func (systemEnvironment) CurrentUser() (profile.UserIdentity, error) {
-	return profile.SystemCurrentUser()
-}
-func (systemEnvironment) LookupUser(name string) (profile.UserIdentity, error) {
-	return profile.SystemLookupUser(name)
-}
-func (systemEnvironment) LookupEnv(name string) (string, bool) { return os.LookupEnv(name) }
-
-func pathWithin(path, parent string) bool {
-	relative, err := filepath.Rel(parent, path)
-	return err == nil && relative != ".." && !strings.HasPrefix(relative, ".."+string(filepath.Separator))
-}
+func pathWithin(path, parent string) bool { return pathutil.Within(path, parent) }
 
 type Environment interface{ LookupEnv(string) (string, bool) }
 type MapEnvironment map[string]string