HS fixes: multi-property transition, take attr with-val, empty form, css-value parsing

- Parser: multi-property transition (width from 0px to 100px height from...)
  with collect-transitions loop. CSS value parsing uses parse-atom + manual
  number+unit concat to avoid greedy string-postfix chaining.
- Compiler: take! passes attr-val and with-val (restored from revert)
- Runtime: hs-empty-target! handles FORM by iterating child inputs,
  hs-starts-with-ic/hs-ends-with-ic for case-insensitive comparison

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

lib/hyperscript/runtime.sx

@@ -542,6 +542,10 @@
                   (dom-set-prop target "checked" false)
                   (dom-set-prop target "value" ""))))
             ((= tag "FORM") (dom-set-inner-html target ""))
+            ((= tag "FORM")
+              (let
+                ((children (host-call target "querySelectorAll" "input, textarea, select")))
+                (for-each (fn (el) (hs-empty-target! el)) children)))
             (true (dom-set-inner-html target ""))))))))
 ;; Collection: joined by
 (define