Move bootstrap migration INSERT into 000.sql

Per review: the SQL file should be self-contained. 000.sql now
includes both the CREATE TABLE and the INSERT OR IGNORE for recording
its own version. Removed the separate INSERT from Go code in
bootstrapMigrationsTable().

internal/database/database.go

@@ -177,14 +177,6 @@ func bootstrapMigrationsTable(ctx context.Context, db *sql.DB, log *slog.Logger)
 		return fmt.Errorf("failed to apply bootstrap migration: %w", err)
 	}
 
-	_, err = db.ExecContext(ctx,
-		"INSERT INTO schema_migrations (version) VALUES (?)",
-		bootstrapVersion,
-	)
-	if err != nil {
-		return fmt.Errorf("failed to record bootstrap migration: %w", err)
-	}
-
 	return nil
 }