Introduce README.md, AI-USE.md. Setup nix-shell for node. Tag personal comments with @PERSONAL-NOTE.

README.md

@@ -0,0 +1,47 @@
+# Picturarium
+
+Picturarium is a small React image gallery using the Lorem Picsum API. It displays paginated image thumbnails, caches loaded pages during the session, and opens selected images in a larger
+modal view. The app uses TypeScript, Material UI, and explicit remote/request state handling for loading and error states.
+
+# Installation
+
+This assumes `node` is installed on your system.
+TODO: specify `git clone` too here.
+
+```bash
+git clone // TODO
+cd picturarium
+npm install
+```
+
+# Execution
+
+After cloning the repo in `picturarium/`:
+
+## dev
+
+You can start a vite dev-server
+
+```bash
+npm run dev
+```
+
+## production
+
+To see production build:
+
+```bash
+npm run build
+npm run preview
+```
+
+# Comments
+
+In this codebase I sometimes use comments that start as
+
+```typescript
+// @PERSONAL_NOTE
+```
+
+These are just there for this particular assignment, and I wouldn't included them in a real codebase.
+They are just notes to let you know why I made specific decisions and how I think about stuff.