feat: sovereign identity flow — NAH! animation + keypair generation

When users click on the legacy email/password form, the form zooms
out and a bold "NAH!" animates in. This transitions to an
"Own your privacy" message with a "Generate Sovereign Identity"
button that creates a new Nostr keypair, logs the user in, and
presents a red glassmorphism "Download your new identity" button
that saves the nsec/npub keypair to a text file.

Uses applesauce PrivateKeyAccount.fromKey() for proper account
registration and persistence.

Co-authored-by: Cursor <cursoragent@cursor.com>

docker-compose.yml

@@ -20,7 +20,7 @@ services:
       context: .
       dockerfile: Dockerfile
       args:
-        CACHEBUST: "22"
+        CACHEBUST: "23"
         VITE_USE_MOCK_DATA: "false"
         VITE_CONTENT_ORIGIN: ${FRONTEND_URL}
         VITE_INDEEHUB_API_URL: /api