nixos/nginx: disable automatic advertise of HTTP/3 protocol support

Automatic advertise in the `http` block about support of HTTP/3
protocol makes it difficult to automatically configure services
to work with it.
HTTP/3 availability must be manually advertised, preferably in
each location block.

nixos/doc/manual/release-notes/rl-2405.section.md

@@ -59,6 +59,18 @@ The pre-existing [services.ankisyncd](#opt-services.ankisyncd.enable) has been m
 - `mkosi` was updated to v19. Parts of the user interface have changed. Consult the
   [release notes](https://github.com/systemd/mkosi/releases/tag/v19) for a list of changes.
 
+- `services.nginx` will no longer advertise HTTP/3 availability automatically. This must now be manually added, preferably to each location block.
+  Example:
+
+  ```nix
+    locations."/".extraConfig = ''
+      add_header Alt-Svc 'h3=":$server_port"; ma=86400';
+    '';
+    locations."^~ /assets/".extraConfig = ''
+      add_header Alt-Svc 'h3=":$server_port"; ma=86400';
+    '';
+
+  ```
 - The `kanata` package has been updated to v1.5.0, which includes [breaking changes](https://github.com/jtroo/kanata/releases/tag/v1.5.0).
 
 - The latest available version of Nextcloud is v28 (available as `pkgs.nextcloud28`). The installation logic is as follows:

nixos/modules/services/web-servers/nginx/default.nix

@@ -408,12 +408,6 @@ let
             ssl_conf_command Options KTLS;
           ''}
 
-          ${optionalString (hasSSL && vhost.quic && vhost.http3)
-            # Advertise that HTTP/3 is available
-          ''
-            add_header Alt-Svc 'h3=":$server_port"; ma=86400';
-          ''}
-
           ${mkBasicAuth vhostName vhost}
 
           ${optionalString (vhost.root != null) "root ${vhost.root};"}

nixos/modules/services/web-servers/nginx/vhost-options.nix

@@ -235,9 +235,9 @@ with lib;
         which can be achieved by setting `services.nginx.package = pkgs.nginxQuic;`
         and activate the QUIC transport protocol
         `services.nginx.virtualHosts.<name>.quic = true;`.
-        Note that HTTP/3 support is experimental and
+        Note that HTTP/3 support is experimental and *not* yet recommended for production.
-        *not* yet recommended for production.
         Read more at https://quic.nginx.org/
+        HTTP/3 availability must be manually advertised, preferably in each location block.
       '';
     };
 
@@ -250,8 +250,7 @@ with lib;
         which can be achieved by setting `services.nginx.package = pkgs.nginxQuic;`
         and activate the QUIC transport protocol
         `services.nginx.virtualHosts.<name>.quic = true;`.
-        Note that special application protocol support is experimental and
+        Note that special application protocol support is experimental and *not* yet recommended for production.
-        *not* yet recommended for production.
         Read more at https://quic.nginx.org/
       '';
     };