Implement persistent Line ordering for project specs and update bible

internal/localdb/migrations.go

@@ -108,6 +108,11 @@ var localMigrations = []localMigration{
 		name: "Deduplicate configuration revisions by spec+price",
 		run:  deduplicateConfigurationVersionsBySpecAndPrice,
 	},
+	{
+		id:   "2026_02_19_local_config_line_no",
+		name: "Add line_no to local_configurations and backfill ordering",
+		run:  addLocalConfigurationLineNo,
+	},
 }
 
 func runLocalMigrations(db *gorm.DB) error {
@@ -806,3 +811,56 @@ func addLocalConfigurationSupportCode(tx *gorm.DB) error {
 	}
 	return nil
 }
+
+func addLocalConfigurationLineNo(tx *gorm.DB) error {
+	type columnInfo struct {
+		Name string `gorm:"column:name"`
+	}
+	var columns []columnInfo
+	if err := tx.Raw(`
+		SELECT name FROM pragma_table_info('local_configurations')
+		WHERE name IN ('line_no')
+	`).Scan(&columns).Error; err != nil {
+		return fmt.Errorf("check local_configurations(line_no) existence: %w", err)
+	}
+	if len(columns) == 0 {
+		if err := tx.Exec(`
+			ALTER TABLE local_configurations
+			ADD COLUMN line_no INTEGER
+		`).Error; err != nil {
+			return fmt.Errorf("add local_configurations.line_no: %w", err)
+		}
+		slog.Info("added line_no to local_configurations")
+	}
+
+	if err := tx.Exec(`
+WITH ranked AS (
+	SELECT
+		id,
+		ROW_NUMBER() OVER (
+			PARTITION BY COALESCE(NULLIF(TRIM(project_uuid), ''), '__NO_PROJECT__')
+			ORDER BY created_at ASC, id ASC
+		) AS rn
+	FROM local_configurations
+	WHERE line_no IS NULL OR line_no <= 0
+)
+UPDATE local_configurations
+SET line_no = (
+	SELECT rn * 10
+	FROM ranked
+	WHERE ranked.id = local_configurations.id
+)
+WHERE id IN (SELECT id FROM ranked)
+`).Error; err != nil {
+		return fmt.Errorf("backfill local_configurations.line_no: %w", err)
+	}
+
+	if err := tx.Exec(`
+		CREATE INDEX IF NOT EXISTS idx_local_configurations_project_line_no
+		ON local_configurations(project_uuid, line_no)
+	`).Error; err != nil {
+		return fmt.Errorf("ensure idx_local_configurations_project_line_no: %w", err)
+	}
+
+	return nil
+}