Wire sexp.js into page template with auto-init and HTMX integration

- Load sexp.js in ~app-layout before body.js
- Auto-process <script type="text/sexp"> tags on DOMContentLoaded
- Re-process after htmx:afterSwap for dynamic content
- Sexp.mount(target, expr, env) for rendering into DOM elements
- Sexp.processScripts() picks up data-components and data-mount tags
- client_components_tag() Python helper serializes Component objects
  back to sexp source for client-side consumption
- 37 parity tests all passing

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

shared/sexp/tests/test_sexp_js.py

@@ -133,6 +133,36 @@ class TestComponents:
         assert html == '<div><span>hi</span></div>'
 
 
+class TestClientComponentsTag:
+    """client_components_tag() generates valid sexp for JS consumption."""
+
+    def test_emits_script_tag(self):
+        from shared.sexp.jinja_bridge import client_components_tag, register_components, _COMPONENT_ENV
+        # Register a test component
+        register_components('(defcomp ~test-cct (&key label) (span label))')
+        try:
+            tag = client_components_tag("test-cct")
+            assert tag.startswith('<script type="text/sexp" data-components>')
+            assert tag.endswith('</script>')
+            assert "defcomp ~test-cct" in tag
+        finally:
+            _COMPONENT_ENV.pop("~test-cct", None)
+
+    def test_roundtrip_through_js(self):
+        """Component emitted by client_components_tag renders identically in JS."""
+        from shared.sexp.jinja_bridge import client_components_tag, register_components, _COMPONENT_ENV
+        register_components('(defcomp ~test-rt (&key title) (div :class "rt" title))')
+        try:
+            tag = client_components_tag("test-rt")
+            # Extract the sexp source from the script tag
+            sexp_source = tag.replace('<script type="text/sexp" data-components>', '').replace('</script>', '')
+            js_html = _js_render('(~test-rt :title "hello")', sexp_source)
+            py_html = py_render(parse('(~test-rt :title "hello")'), _COMPONENT_ENV)
+            assert js_html == py_html
+        finally:
+            _COMPONENT_ENV.pop("~test-rt", None)
+
+
 class TestPythonParity:
     """JS string renderer matches Python renderer output."""