Remove backwards compat code: no installed base pre-1.0

- Simplify bootstrapMigrationsTable to just check table existence and
  apply 000.sql if missing — no legacy DB detection
- Remove ensureBootstrapVersionRecorded (legacy backfill path)
- Remove applyBootstrapMigration (separate helper, now inlined)
- Remove TestBootstrapMigrationsTable_ExistingTableBackwardsCompat
- Simplify 000.sql header comment

internal/database/database.go

@@ -148,9 +148,7 @@ func collectMigrations() ([]string, error) {
 }
 
 // bootstrapMigrationsTable ensures the schema_migrations table exists
-// by applying 000.sql directly. For databases that already have the
-// table (created by older code), it records version "000" for
-// consistency.
+// by applying 000.sql if the table is missing.
 func bootstrapMigrationsTable(ctx context.Context, db *sql.DB, log *slog.Logger) error {
 	var tableExists int
 
@@ -162,47 +160,9 @@ func bootstrapMigrationsTable(ctx context.Context, db *sql.DB, log *slog.Logger)
 	}
 
 	if tableExists > 0 {
-		return ensureBootstrapVersionRecorded(ctx, db, log)
-	}
-
-	return applyBootstrapMigration(ctx, db, log)
-}
-
-// ensureBootstrapVersionRecorded checks whether version "000" is already
-// recorded in an existing schema_migrations table and inserts it if not.
-func ensureBootstrapVersionRecorded(ctx context.Context, db *sql.DB, log *slog.Logger) error {
-	var recorded int
-
-	err := db.QueryRowContext(ctx,
-		"SELECT COUNT(*) FROM schema_migrations WHERE version = ?",
-		bootstrapVersion,
-	).Scan(&recorded)
-	if err != nil {
-		return fmt.Errorf("failed to check bootstrap migration status: %w", err)
-	}
-
-	if recorded > 0 {
 		return nil
 	}
 
-	_, err = db.ExecContext(ctx,
-		"INSERT INTO schema_migrations (version) VALUES (?)",
-		bootstrapVersion,
-	)
-	if err != nil {
-		return fmt.Errorf("failed to record bootstrap migration: %w", err)
-	}
-
-	if log != nil {
-		log.Info("recorded bootstrap migration for existing table", "version", bootstrapVersion)
-	}
-
-	return nil
-}
-
-// applyBootstrapMigration reads and executes 000.sql to create the
-// schema_migrations table on a fresh database.
-func applyBootstrapMigration(ctx context.Context, db *sql.DB, log *slog.Logger) error {
 	content, err := schemaFS.ReadFile("schema/000.sql")
 	if err != nil {
 		return fmt.Errorf("failed to read bootstrap migration 000.sql: %w", err)
@@ -225,10 +185,6 @@ func applyBootstrapMigration(ctx context.Context, db *sql.DB, log *slog.Logger)
 		return fmt.Errorf("failed to record bootstrap migration: %w", err)
 	}
 
-	if log != nil {
-		log.Info("bootstrap migration applied successfully", "version", bootstrapVersion)
-	}
-
 	return nil
 }