Skip vaultik's own index and PID file in a backup (closes #421)

The default config backs up the home directory, which holds vaultik's local index and PID file, so a backup stored a torn copy of the index it was writing. The scan now skips the index, its SQLite side files and the PID file whatever the config says, including when index_path or its directory is a symlink. database purge removes the same list of index files.

Model: opus-5-5

internal/cli/database_test.go

@@ -5,9 +5,11 @@ import (
 	"errors"
 	"io"
 	"os"
+	"path/filepath"
 	"strings"
 	"testing"
 
+	"sneak.berlin/go/vaultik/internal/database"
 	"sneak.berlin/go/vaultik/internal/vaultik"
 )
 
@@ -46,3 +48,28 @@ func TestDatabaseDeleteDeclinedIsError(t *testing.T) {
 			out.String())
 	}
 }
+
+// TestDatabaseDeleteRemovesSideFiles checks that the side files SQLite
+// keeps beside the database file are deleted with it.
+//
+//nolint:paralleltest // mutates the process-global rootFlags
+func TestDatabaseDeleteRemovesSideFiles(t *testing.T) {
+	dir := t.TempDir()
+	dbPath, cfgPath := seedDatabaseDeleteConfig(t, dir)
+
+	indexFiles := database.IndexFiles(dbPath)
+	for _, indexFile := range indexFiles {
+		seedFile(t, dir, filepath.Base(indexFile), "data")
+	}
+
+	setRootFlags(t, RootFlags{ConfigPath: cfgPath})
+
+	mustExecute(t, newDatabaseDeleteCommand(), "--force")
+
+	for _, indexFile := range indexFiles {
+		_, err := os.Stat(indexFile)
+		if !os.IsNotExist(err) {
+			t.Errorf("database delete left %s: stat err = %v", indexFile, err)
+		}
+	}
+}