feat(storage): define StorageAdapter interface types + scaffold package

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/storage/src/index.ts

@@ -0,0 +1 @@
+export type { StorageAdapter, StorageConfig } from './types.js';

packages/storage/src/types.ts

@@ -0,0 +1,43 @@
+export interface StorageAdapter {
+  readonly name: string;
+
+  create<T extends Record<string, unknown>>(
+    collection: string,
+    data: T,
+  ): Promise<T & { id: string }>;
+
+  read<T extends Record<string, unknown>>(collection: string, id: string): Promise<T | null>;
+
+  update(collection: string, id: string, data: Record<string, unknown>): Promise<boolean>;
+
+  delete(collection: string, id: string): Promise<boolean>;
+
+  find<T extends Record<string, unknown>>(
+    collection: string,
+    filter?: Record<string, unknown>,
+    opts?: {
+      limit?: number;
+      offset?: number;
+      orderBy?: string;
+      order?: 'asc' | 'desc';
+    },
+  ): Promise<T[]>;
+
+  findOne<T extends Record<string, unknown>>(
+    collection: string,
+    filter: Record<string, unknown>,
+  ): Promise<T | null>;
+
+  count(collection: string, filter?: Record<string, unknown>): Promise<number>;
+
+  transaction<T>(fn: (tx: StorageAdapter) => Promise<T>): Promise<T>;
+
+  migrate(): Promise<void>;
+
+  close(): Promise<void>;
+}
+
+export type StorageConfig =
+  | { type: 'postgres'; url: string }
+  | { type: 'sqlite'; path: string }
+  | { type: 'files'; dataDir: string; format?: 'json' | 'md' };