handler-source: fix keywords, add syntax highlighting

Keywords were printed as strings because list treated :path as kwargs.
Now uses make-keyword to build keyword nodes. Output goes through
highlight for syntax coloring.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

sx/sx/data/helpers.sx

@@ -38,17 +38,26 @@
             (csrf (get hdef "csrf"))
             (returns (or (get hdef "returns") "element"))
             (params (or (get hdef "params") (list)))
-            (body (get hdef "body")))
-          (pretty-print
-            (list
-              (make-symbol "defhandler")
-              (make-symbol name)
-              :path path
-              :method (make-keyword method)
-              :csrf csrf
-              :returns returns
-              params
-              body)))))))
+            (body (get hdef "body"))
+            (parts (list (make-symbol "defhandler") (make-symbol name))))
+          (let
+            ((parts (append parts (list (make-keyword "path") path)))
+              (parts
+                (append
+                  parts
+                  (list (make-keyword "method") (make-keyword method))))
+              (parts
+                (if
+                  (not csrf)
+                  (append parts (list (make-keyword "csrf") false))
+                  parts))
+              (parts
+                (if
+                  (not (= returns "element"))
+                  (append parts (list (make-keyword "returns") returns))
+                  parts))
+              (parts (append parts (list params body))))
+            (highlight (pretty-print parts))))))))
 
 (define _spec-dirs (list "spec" "web" "shared/sx/ref" "lib"))