pnpm install does not work

it seems that the project wants to be built as part of a workspace that also contains electric-sql itself:

```
% pnpm install
Scope: all 3 workspace projects
/Users/christoph/Projects/ext/electric-sql/electric-ai-chat/packages/app:
 ERR_PNPM_WORKSPACE_PKG_NOT_FOUND  In packages/app: "@electric-sql/client@workspace:*" is in the dependencies but no package named "@electric-sql/client" is present in the workspace

This error happened while installing a direct dependency of /Users/christoph/Projects/ext/electric-sql/electric-ai-chat/packages/app

Packages found in the workspace:
Progress: resolved 0, reused 1, downloaded 0, added 0
```