Cache-bust wasm scripts, fix orchestration.sx paren balance

- Add wasm_hash (MD5 of sx_browser.bc.js) to shell template
- Script tags: /wasm/sx_browser.bc.js?v={hash}, /wasm/sx-platform.js?v={hash}
- Pass wasm_hash through helpers.py and ocaml_bridge.py
- Fix missing close paren in bind-sse-swap (broke SX parsing)

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

shared/sx/ocaml_bridge.py

@@ -190,7 +190,7 @@ class OcamlBridge:
         # Only inject small, safe values as kernel variables.
         # Large/complex blobs use placeholder tokens at render time.
         for key in ("component_hash", "sx_css_classes", "asset_url",
-                    "sx_js_hash", "body_js_hash"):
+                    "sx_js_hash", "body_js_hash", "wasm_hash"):
             val = static.get(key) or ""
             var = f"__shell-{key.replace('_', '-')}"
             defn = f'(define {var} "{_escape(str(val))}")'
@@ -268,7 +268,7 @@ class OcamlBridge:
                                 "sx_css", "inline_css", "inline_head_js"}
             placeholders = {}
             static_keys = {"component_hash", "sx_css_classes", "asset_url",
-                           "sx_js_hash", "body_js_hash",
+                           "sx_js_hash", "body_js_hash", "wasm_hash",
                            "head_scripts", "body_scripts"}
             # page_source is SX wire format that may contain \" escapes.
             # Send via binary blob protocol to avoid double-escaping