Fix circular dependencies in migration system

- Remove MigrationManager export from index.ts
- Add comment explaining why migrations are defined in two places
- Keep migrations defined in both cache.ts and index.ts to avoid circular imports

🦊 Generated with Crush
Co-Authored-By: Crush <[e-mail]>

src/cache.ts

···
    */
   private async runMigrations() {
     try {
+      // Define migrations directly here to avoid circular dependencies
+      // Note: We define migrations both here and in migrations/index.ts
+      // This is intentional to prevent circular imports
       const migrations = [
         endpointGroupingMigration,
         logGroupingMigration

src/migrations/index.ts

···
 import { endpointGroupingMigration } from "./endpointGroupingMigration";
 import { logGroupingMigration } from "./logGroupingMigration";
 import { Migration } from "./types";
-import { MigrationManager } from "./migrationManager";
 
 // Export all migrations
-export const migrations: Migration[] = [
+export const migrations = [
   endpointGroupingMigration,
   logGroupingMigration,
   // Add new migrations here
 ];
 
-// Export the migration manager and types
-export { MigrationManager, Migration };
+// Export the migration types
+export { Migration };