HS parser/compiler/mock: fix 31 test failures across 7 issues

Parser:
- Relax (number? v) to v in parse-one-transition so (expr)unit works
- Add (match-kw "then") before parse-cmd-list in parse-for-cmd
- Handle "indexed by" syntax alongside "index" in for loops
- Add "indexed" to hs-keywords to prevent unit-suffix consumption

Compiler:
- Use map-indexed instead of for-each for indexed for-loops

Test generator:
- Preserve \" escapes in process_hs_val via placeholder/restore

Mock DOM:
- Coerce insertAdjacentHTML values via dom_stringify (match browser)

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

lib/hyperscript/compiler.sx

@@ -267,10 +267,10 @@
           (if
             (and (> (len ast) 4) (= (nth ast 4) :index))
             (list
-              (quote for-each)
+              (quote map-indexed)
               (list
                 (quote fn)
-                (list (make-symbol var-name) (make-symbol (nth ast 5)))
+                (list (make-symbol (nth ast 5)) (make-symbol var-name))
                 body)
               collection)
             (list

lib/hyperscript/parser.sx

@@ -1223,10 +1223,10 @@
                 (let
                   ((prop (cond ((= (tp-type) "style") (get (adv!) "value")) ((= (tp-val) "my") (do (adv!) (if (= (tp-type) "style") (get (adv!) "value") (get (adv!) "value")))) (true (get (adv!) "value")))))
                   (let
-                    ((from-val (if (match-kw "from") (let ((v (parse-atom))) (if (and (number? v) (= (tp-type) "ident") (not (hs-keyword? (tp-val)))) (let ((unit (get (adv!) "value"))) (list (quote string-postfix) v unit)) v)) nil)))
+                    ((from-val (if (match-kw "from") (let ((v (parse-atom))) (if (and v (= (tp-type) "ident") (not (hs-keyword? (tp-val)))) (let ((unit (get (adv!) "value"))) (list (quote string-postfix) v unit)) v)) nil)))
                     (expect-kw! "to")
                     (let
-                      ((value (let ((v (parse-atom))) (if (and (number? v) (= (tp-type) "ident") (not (hs-keyword? (tp-val)))) (let ((unit (get (adv!) "value"))) (list (quote string-postfix) v unit)) v))))
+                      ((value (let ((v (parse-atom))) (if (and v (= (tp-type) "ident") (not (hs-keyword? (tp-val)))) (let ((unit (get (adv!) "value"))) (list (quote string-postfix) v unit)) v))))
                       (let
                         ((dur (if (match-kw "over") (let ((v (parse-atom))) (if (and (number? v) (= (tp-type) "ident") (not (hs-keyword? (tp-val)))) (let ((unit (get (adv!) "value"))) (list (quote string-postfix) v unit)) v)) nil)))
                         (let
@@ -1521,9 +1521,9 @@
             (let
               ((collection (parse-expr)))
               (let
-                ((idx (if (match-kw "index") (let ((iname (tp-val))) (adv!) iname) nil)))
+                ((idx (cond ((match-kw "index") (let ((iname (tp-val))) (adv!) iname)) ((match-kw "indexed") (do (match-kw "by") (let ((iname (tp-val))) (adv!) iname))) (true nil))))
                 (let
-                  ((body (parse-cmd-list)))
+                  ((body (do (match-kw "then") (parse-cmd-list))))
                   (match-kw "end")
                   (if
                     idx

lib/hyperscript/tokenizer.sx

@@ -104,6 +104,7 @@
     "detail"
     "sender"
     "index"
+    "indexed"
     "increment"
     "decrement"
     "append"