Add app screenshots to README

Capture Create, Library, Editor, and Settings pages via Playwright;
embed in a Screenshots section so they render on the repo home page.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

README.md

@@ -18,6 +18,26 @@ You stay in control: every question can be edited, regenerated with a steering n
 
 ---
 
+## Screenshots
+
+**Create** — paste, upload, or pull from a URL, then set parameters and generate.
+
+![Create an assignment](docs/screenshots/create.png)
+
+**Library** — every assignment you've made, stored locally on your machine.
+
+![Library](docs/screenshots/library.png)
+
+**Editor** — per-question editing with `✓ Verified` / `⚠ Check this` accuracy badges and source quotes.
+
+![Question editor](docs/screenshots/editor.png)
+
+**Settings** — pick your AI provider (local or cloud) and set your school profile.
+
+![Settings](docs/screenshots/settings.png)
+
+---
+
 ## What you need
 
 - **Docker** — [Docker Desktop](https://www.docker.com/products/docker-desktop/) on macOS/Windows, or Docker Engine on Linux. That's the only thing you install.