chore: initialize frontend repo with teaching terminology updates

Add the current frontend codebase with a baseline .gitignore and update piano-specific UI terms to teaching-oriented terms for the current product context.

Made-with: Cursor

container/init.sh

@@ -0,0 +1,13 @@
+#!/bin/bash
+set -x
+
+echo "UC_PORT: ${UC_PORT}"
+echo "WS_PORT: ${WS_PORT}"
+
+# shellcheck disable=SC2044
+for FILE in $(find /etc/nginx/conf.d/*); do
+    sed -i -e "s|UC_PORT|${UC_PORT}|" -e "s|WS_PORT|${WS_PORT}|" "${FILE}"
+done
+
+/usr/sbin/nginx
+sh