feat(api): add fleet snapshots and durable event stream

apps/api/src/infrastructure/database/migrations.ts

@@ -270,6 +270,18 @@ export const MIGRATIONS: readonly Migration[] = [
       'CREATE INDEX idx_operation_preparations_status_expires_at ON operation_preparations(status, expires_at)',
     ],
   },
+  {
+    id: 6,
+    name: 'durable-event-journal',
+    statements: [
+      `CREATE TABLE event_journal (
+        sequence INTEGER PRIMARY KEY AUTOINCREMENT,
+        public_id TEXT NOT NULL UNIQUE,
+        envelope_json TEXT NOT NULL
+      )`,
+      'CREATE INDEX idx_event_journal_sequence ON event_journal(sequence)',
+    ],
+  },
 ];
 
 const createMigrationsTable = `CREATE TABLE schema_migrations (