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>

roles/web-static/templates/nginx.conf.j2

@@ -30,6 +30,22 @@ server {
     root {{ (app_catalog[a.name].webroot_pattern | default(web_static_root ~ '/{env}_' ~ a.name)) | replace('{env}', a.env) }};
     index index.html;
 
+{% if app_catalog[a.name].exact_root_files | default(false) %}
+    # Crawlers must get these files, never the SPA index.html fallback.
+    location = /robots.txt {
+        default_type text/plain;
+        try_files /robots.txt =404;
+    }
+    location = /sitemap.xml {
+        default_type application/xml;
+        try_files /sitemap.xml =404;
+    }
+    location = /llms.txt {
+        default_type text/plain;
+        try_files /llms.txt =404;
+    }
+{% endif %}
+
 {% if app_catalog[a.name].error_page_404 | default('') %}
     error_page 404 {{ app_catalog[a.name].error_page_404 }};