Add brainstorm server with WebSocket support, helpers, and tests

WebSocket server for real-time browser communication during brainstorming
sessions. Includes browser helper library for event capture, shell scripts
for server lifecycle management with session isolation and persistent
mockup storage, and integration tests.

Co-Authored-By: Drew Ritter <drew@ritter.dev>

tests/brainstorm-server/package.json

@@ -0,0 +1,10 @@
+{
+  "name": "brainstorm-server-tests",
+  "version": "1.0.0",
+  "scripts": {
+    "test": "node server.test.js"
+  },
+  "dependencies": {
+    "ws": "^8.19.0"
+  }
+}