Extend CDN cache time

We had a very brief outage due to Scaleway issues, and this resulted in
visible downtime because the cache time was too short. No real reason
not to extend this, since we purge the cache on deploy anyway.

Author: pimterry

Caddyfile

@@ -9,11 +9,10 @@
     try_files {path} /index.html
     file_server
 
-    # Cache responses for 1 minute, validate async during next 10 minutes, or
-    # continue serving old data as-is for up to 24 hours if this server stops
-    # responding/returns errors.
+    # Cache responses for 1 minute (local)/1h (CDN - invalidated on deploy), validate async during the next 10
+    # minutes, or continue using old data as-is for up to 24 hours if this server stops responding/returns errors.
     @get method GET
-    header @get Cache-Control "public, max-age=60, stale-while-revalidate=600, stale-if-error=86400"
+    header @get Cache-Control "public, max-age=60, s-maxage=3600, stale-while-revalidate=600, stale-if-error=86400"
 
     header Content-Security-Policy "frame-ancestors 'none'"
     header Referrer-Policy "strict-origin"