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.go

@@ -6,6 +6,7 @@ import (
 
 	"github.com/spf13/cobra"
 	"sneak.berlin/go/vaultik/internal/config"
+	"sneak.berlin/go/vaultik/internal/database"
 	"sneak.berlin/go/vaultik/internal/log"
 	"sneak.berlin/go/vaultik/internal/vaultik"
 )
@@ -100,18 +101,16 @@ Use --force to skip the confirmation prompt.`,
 				}
 			}
 
-			// Delete the database file
-			err = os.Remove(dbPath)
-			if err != nil {
-				return fmt.Errorf("failed to delete database: %w", err)
+			// Delete the database file and its side files. A side file
+			// may not exist, so only failing to delete the database file
+			// is an error.
+			for _, indexFile := range database.IndexFiles(dbPath) {
+				err = os.Remove(indexFile)
+				if err != nil && indexFile == dbPath {
+					return fmt.Errorf("failed to delete database: %w", err)
+				}
 			}
 
-			// Also delete WAL and SHM files if they exist
-			walPath := dbPath + "-wal"
-			shmPath := dbPath + "-shm"
-			_ = os.Remove(walPath) // Ignore errors - files may not exist
-			_ = os.Remove(shmPath)
-
 			out.Infof("Local state database deleted: %s.", dbPath)
 			log.Info("Local state database deleted", "path", dbPath)