README: document the evote cockpit live-math teaching view

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

README.md

@@ -68,6 +68,9 @@ make test           # runs cargo test + go test ./...
 ./evote netdemo --voters 10 --options 3
 ./evote netdemo --voters 3 --options 2 --verbose   # log every signed message
 
+# Watch the cryptography execute as live typeset math in the browser
+./evote cockpit --voters 3 --options 3        # open http://localhost:8090
+
 # Serve presentations on local network (for iPad viewing)
 ./evote serve --port 8080
 
@@ -75,6 +78,14 @@ make test           # runs cargo test + go test ./...
 ./evote present
 ```
 
+The `cockpit` command is a teaching instrument: it runs the full multi-party
+ceremony and streams **every cryptographic operation** — sampling, ElGamal
+encryption, Fiat-Shamir challenges, the Bayer-Groth shuffle, Ed25519 signatures,
+X25519 key agreement — to a browser page that renders each as **typeset
+mathematics with the real runtime values**, the instant it executes. The math is
+native MathML (no libraries, offline); a stakeholder sidebar highlights the acting
+party and a phase timeline tracks setup→cards→voting→tally→verify.
+
 The `demo` command runs the whole protocol in one process. `netdemo` runs the
 **multi-party** architecture: every party is a separate endpoint holding only its
 own private state, and every message between them is Ed25519-signed (and, for