Add multi-account OAuth, Obsidian integration, product assets, and test tooling

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

product/site/nginx-site.conf

@@ -0,0 +1,19 @@
+server {
+    listen 8080;
+    server_name squaremcp.com www.squaremcp.com;
+
+    root /usr/share/nginx/html;
+    index index.html;
+
+    location / {
+        try_files $uri $uri/ /index.html;
+    }
+
+    location = /index.html {
+        add_header Cache-Control "no-cache";
+    }
+
+    location ~* \.(css|js)$ {
+        add_header Cache-Control "public, max-age=3600";
+    }
+}