Point dta_webapp webroot at realpath.app paths (closes #12)

Align webroot_pattern and docs with dta_webapp builds under /var/www/{env}.realpath.app/html so deploy and web-static nginx serve the same dirs.

inventory/group_vars/all.yml

@@ -77,7 +77,7 @@ app_catalog:
     subdir: ditch-the-agent
     # Document root served by nginx and written by `npm run build:<env>`.
     # {env} is replaced with the entry's env (beta/prod).
-    webroot_pattern: "/var/www/{env}.app.ditchtheagent/html"
+    webroot_pattern: "/var/www/{env}.realpath.app/html"
     # deploy runs `npm ci` then `npm run build:<env>`; that script writes to
     # {{ web_static_root }}/<env>_dta_webapp (beta/prod), served by web-static.
   scha: