fix(shared): expose ./crypto/testBackend in package exports

Removes the @shared Vite-alias workaround in userIdentity.test.ts so
tsc can resolve the import without an extra paths entry.

apps/desktop/src/lib/userIdentity.test.ts

@@ -1,11 +1,7 @@
 import { describe, expect, it, beforeEach, vi, beforeAll } from 'vitest';
 
 import { setCryptoBackend } from '@chat-app/shared/crypto';
-// `@chat-app/shared` does not expose `./crypto/testBackend` in its package
-// exports map (only `./crypto`). Reach the test backend through the local
-// `@shared` Vite alias (configured in apps/desktop/vite.config.ts) so the
-// import resolves at test time without modifying the shared package.
-import { makeWasmTestBackend } from '@shared/crypto/testBackend';
+import { makeWasmTestBackend } from '@chat-app/shared/crypto/testBackend';
 
 beforeAll(async () => { setCryptoBackend(await makeWasmTestBackend()); });
 

packages/shared/package.json

@@ -10,6 +10,7 @@
     ".": "./src/index.ts",
     "./supabase": "./src/supabase/index.ts",
     "./crypto": "./src/crypto/index.ts",
+    "./crypto/testBackend": "./src/crypto/testBackend.ts",
     "./auth": "./src/auth/index.ts",
     "./chat": "./src/chat/index.ts",
     "./admin": "./src/admin/index.ts",