HS: parse-feat paren-open adds string-postfix check (+1 test)

parse-feat's paren-open handler stripped the grouping parens and
returned the inner feature, leaving any trailing ident (like `em`)
as a separate top-level feature. After consuming the closing paren,
now checks if the next token is a non-keyword ident or `%` op and
wraps as (string-postfix inner unit), making `(0 + 1) em` → "1em".

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/hyperscript/parser.sx

@@ -987,7 +987,7 @@
               (do
                 (when
                   (and
-                    (number? left)
+                    (or (number? left) (list? left))
                     (= (tp-type) "ident")
                     (not
                       (or
@@ -3113,7 +3113,23 @@
                   (let
                     ((inner (parse-feat)))
                     (if (= (tp-type) "paren-close") (adv!) nil)
-                    inner)))
+                    (if
+                      (and
+                        inner
+                        (or
+                          (and
+                            (= (tp-type) "ident")
+                            (not
+                              (or
+                                (= (tp-val) "then")
+                                (= (tp-val) "end")
+                                (= (tp-val) "else")
+                                (= (tp-val) "otherwise"))))
+                          (and (= (tp-type) "op") (= (tp-val) "%"))))
+                      (let
+                        ((unit (tp-val)))
+                        (do (adv!) (list (quote string-postfix) inner unit)))
+                      inner))))
               ((= val "on") (do (adv!) (parse-on-feat)))
               ((= val "init") (do (adv!) (parse-init-feat)))
               ((= val "def") (do (adv!) (parse-def-feat)))

shared/static/wasm/sx/hs-parser.sx

@@ -987,7 +987,7 @@
               (do
                 (when
                   (and
-                    (number? left)
+                    (or (number? left) (list? left))
                     (= (tp-type) "ident")
                     (not
                       (or
@@ -3113,7 +3113,23 @@
                   (let
                     ((inner (parse-feat)))
                     (if (= (tp-type) "paren-close") (adv!) nil)
-                    inner)))
+                    (if
+                      (and
+                        inner
+                        (or
+                          (and
+                            (= (tp-type) "ident")
+                            (not
+                              (or
+                                (= (tp-val) "then")
+                                (= (tp-val) "end")
+                                (= (tp-val) "else")
+                                (= (tp-val) "otherwise"))))
+                          (and (= (tp-type) "op") (= (tp-val) "%"))))
+                      (let
+                        ((unit (tp-val)))
+                        (do (adv!) (list (quote string-postfix) inner unit)))
+                      inner))))
               ((= val "on") (do (adv!) (parse-on-feat)))
               ((= val "init") (do (adv!) (parse-init-feat)))
               ((= val "def") (do (adv!) (parse-def-feat)))