Serve Hesychia crawler files as static text instead of the app shell.

Exact locations return robots.txt, sitemap.xml, and llms.txt, or 404.
Closes #43.

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

inventory/group_vars/all.yml

@@ -119,6 +119,8 @@ app_catalog:
     # 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}.chat.aimloperations/html"
+    # /robots.txt, /sitemap.xml, and /llms.txt must not fall through to index.html.
+    exact_root_files: true
   chat_backend:
     type: django
     repo: "{{ git_base_url }}/ai_ml_operations/chat_backend.git"