LLM-first kit planning: read use-case intent and map to in-stock categories instead of defaulting novel requests to vlogging

Allow multiple email domains for sign-in (altafhvali.com, gmail.com)

Add email/password sign-in and restrict sign-in to altafhvali.com

Surface Firestore init error via /health for diagnostics

Make kit edits incremental: pin existing picks/brand so add/remove doesn't reshuffle the whole bundle

Google auth + chat-quality + mobile

AHV Assistant backend