Keep startup database rebuilds out of memory

src/lib/server/hosts/schema.ts

@@ -2,6 +2,7 @@ import { createHash } from 'node:crypto';
 import { ensureFileBlobSchema, migrationRows, packFileJson, referenceBlobs } from '../db/file-blobs.js';
 import { retentionClocks } from '../db/retention-clocks.js';
 import { installHistoryCounts } from './history-counts.js';
+import { migrationStep } from '../db/connection.js';
 import type Database from 'better-sqlite3';
 import { successfulObservationSql, routineObservationSql, operationTargetSql, importantOperationSql } from './observations.js';
 
@@ -10,6 +11,11 @@ export function ensureHostSchema(handle: Database.Database): void {
     if (initialized.has(handle)) return;
     // Background readers open only after controller migrations have completed.
     if (handle.readonly) { initialized.add(handle); return; }
+    migrationStep('host schema and saved command files', () => migrateHostSchema(handle));
+    initialized.add(handle);
+}
+
+function migrateHostSchema(handle: Database.Database): void {
     ensureFileBlobSchema(handle);
     handle.exec(`
         CREATE TABLE IF NOT EXISTS ec_hosts (
@@ -189,5 +195,4 @@ export function ensureHostSchema(handle: Database.Database): void {
         DELETE FROM file_blob_references WHERE owner_type IN ('operation','operation-result') AND owner_id=NEW.id; END;`);
     retentionClocks(handle, { ec_host_operations: ['created_at', 'updated_at'] });
     installHistoryCounts(handle);
-    initialized.add(handle);
 }