HS: select returns selected text (+1 test)

Runtime gains hs-get-selection: prefers window.__test_selection stash,
falls back to real getSelection().toString(). Compiler rewrites
`(ref "selection")` to `(hs-get-selection)`. Generator detects the
createRange + setStart/setEnd + addRange block and emits a single
host-set! on __test_selection with the text slice; sidesteps the need
for a fully propagating DOM range/text-node mock.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/playwright/generate-sx-tests.py

@@ -1142,6 +1142,30 @@ def parse_dev_body(body, elements, var_names):
                 ops.append(f'(if (dom-has-class? {target} "{cls}") (dom-remove-class {target} "{cls}") (dom-add-class {target} "{cls}"))')
             continue
 
+        # evaluate(() => { var range = document.createRange();
+        #   var textNode = document.getElementById(ID).firstChild;
+        #   range.setStart(textNode, N); range.setEnd(textNode, M);
+        #   window.getSelection().addRange(range); })
+        # -> set window.__test_selection to text slice
+        m = re.search(
+            r"document\.createRange\(\)[\s\S]*?document\.getElementById\(\s*['\"]([\w-]+)['\"]\s*\)[\s\S]*?setStart\([^,]+,\s*(\d+)\s*\)[\s\S]*?setEnd\([^,]+,\s*(\d+)\s*\)",
+            stmt_na,
+        )
+        if m and seen_html:
+            el_id = m.group(1)
+            start = int(m.group(2))
+            end = int(m.group(3))
+            # Find the element whose id matches, pull its inner text/HTML
+            selected_text = None
+            for el in elements:
+                if el.get('id') == el_id:
+                    txt = el.get('inner') or ''
+                    selected_text = txt[start:end]
+                    break
+            if selected_text is not None:
+                ops.append(f'(host-set! (host-global "window") "__test_selection" "{selected_text}")')
+                continue
+
         if not seen_html:
             continue
         if add_action(stmt_na):