node16: Update missing extensions index.ts

[FossPrime]

Some exports are still not found under node16 moduleResolution. In the other NodeNext PR I forgot to fix re-exports... and only addressed imports.

• useAuth
• https://unpkg.com/browse/feathers-pinia@3.0.4/dist/stores/index.d.ts
• https://unpkg.com/browse/feathers-pinia@3.0.4/dist/use-find-get/index.d.ts
• https://unpkg.com/browse/feathers-pinia@3.0.4/dist/utils/index.d.ts

[marshallswain]

Is this ready?

[marshallswain]

lmao. I didn't even open the files changed. Looks like I've been unhealthily busy. :grin: