feat(web-arm): add AVIF image support to cloonar.dev

Implement AVIF image content negotiation with WebP fallback for
cloonar.dev website. Browser will receive AVIF if supported and
available, otherwise WebP, falling back to original JPEG/PNG.

- Add AVIF-first content negotiation in image location block
- Maintain existing WebP fallback logic
- Include .avif in long-term cache headers (365d)
- Add Vary: Accept header for proper CDN/browser caching

AVIF files should be placed at /avif/$request_uri.avif to be served.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

hosts/web-arm/sites/cloonar.dev.nix

@@ -14,20 +14,42 @@ in {
     '';
 
     locations."~* \.(jpe?g|png)$".extraConfig = ''
-      set $red Z;
+      set $img_format Z;
+
+      # Check for AVIF support (highest priority)
+      if ($http_accept ~* "avif") {
+          set $img_format A;
+      }
+
+      if (-f $document_root/avif/$request_uri.avif) {
+          set $img_format "''${img_format}V";
+      }
+
+      # Serve AVIF if supported and available
+      if ($img_format = "AV") {
+          add_header Vary Accept;
+          rewrite ^ /avif/$request_uri.avif break;
+      }
+
+      # Reset and check for WebP support (fallback)
+      set $img_format Z;
 
       if ($http_accept ~* "webp") {
-          set $red A;
+          set $img_format W;
       }
 
       if (-f $document_root/webp/$request_uri.webp) {
-          set $red "''${red}B";
+          set $img_format "''${img_format}P";
       }
 
-      if ($red = "AB") {
+      # Serve WebP if supported and available
+      if ($img_format = "WP") {
           add_header Vary Accept;
-          rewrite ^ /webp/$request_uri.webp;
+          rewrite ^ /webp/$request_uri.webp break;
       }
+
+      # If neither AVIF nor WebP matched, serve original format
+      add_header Vary Accept;
     '';
 
     locations."^~ /vcards/".extraConfig = ''
@@ -40,7 +62,7 @@ in {
         try_files $uri $uri/ /vcards/index.php$is_args$args;
     '';
 
-    locations."~* \.(js|jpg|gif|png|webp|css|woff2)$".extraConfig = ''
+    locations."~* \.(js|jpg|gif|png|webp|avif|css|woff2)$".extraConfig = ''
       expires 365d;
       add_header Pragma "public";
       add_header Cache-Control "public";