Bootstrap stores + event bridge, add island hydration to boot.sx

- signals.sx: fix has? → has-key?, add def-store/use-store/clear-stores
  (L3 named stores), emit-event/on-event/bridge-event (event bridge)
- boot.sx: add sx-hydrate-islands, hydrate-island, dispose-island
  for client-side island hydration from SSR output
- bootstrap_js.py: add RENAMES, platform fns (domListen, eventDetail,
  domGetData, jsonParse), public API exports for all new functions
- bootstrap_py.py: add RENAMES, server-side no-op stubs for DOM events
- Regenerate sx-ref.js (with boot adapter) and sx_ref.py
- Update reactive-islands status: hydration, stores, bridge all spec'd

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

shared/sx/ref/bootstrap_js.py

@@ -165,6 +165,13 @@ class JSEmitter:
             "*batch-depth*": "_batchDepth",
             "*batch-queue*": "_batchQueue",
             "*island-scope*": "_islandScope",
+            "*store-registry*": "_storeRegistry",
+            "def-store": "defStore",
+            "use-store": "useStore",
+            "clear-stores": "clearStores",
+            "emit-event": "emitEvent",
+            "on-event": "onEvent",
+            "bridge-event": "bridgeEvent",
             "macro?": "isMacro",
             "primitive?": "isPrimitive",
             "get-primitive": "getPrimitive",
@@ -314,6 +321,8 @@ class JSEmitter:
             "dom-add-class": "domAddClass",
             "dom-remove-class": "domRemoveClass",
             "dom-dispatch": "domDispatch",
+            "dom-listen": "domListen",
+            "event-detail": "eventDetail",
             "dom-query": "domQuery",
             "dom-query-all": "domQueryAll",
             "dom-tag-name": "domTagName",
@@ -322,6 +331,8 @@ class JSEmitter:
             "dom-child-nodes": "domChildNodes",
             "dom-remove-children-after": "domRemoveChildrenAfter",
             "dom-set-data": "domSetData",
+            "dom-get-data": "domGetData",
+            "json-parse": "jsonParse",
             "dict-has?": "dictHas",
             "dict-delete!": "dictDelete",
             "process-bindings": "processBindings",
@@ -508,6 +519,9 @@ class JSEmitter:
             "process-component-script": "processComponentScript",
             "SX_VERSION": "SX_VERSION",
             "boot-init": "bootInit",
+            "sx-hydrate-islands": "sxHydrateIslands",
+            "hydrate-island": "hydrateIsland",
+            "dispose-island": "disposeIsland",
             "resolve-suspense": "resolveSuspense",
             "resolve-mount-target": "resolveMountTarget",
             "sx-render-with-env": "sxRenderWithEnv",
@@ -2870,6 +2884,16 @@ PLATFORM_DOM_JS = """
     return el.dispatchEvent(evt);
   }
 
+  function domListen(el, name, handler) {
+    if (!_hasDom || !el) return function() {};
+    el.addEventListener(name, handler);
+    return function() { el.removeEventListener(name, handler); };
+  }
+
+  function eventDetail(e) {
+    return (e && e.detail != null) ? e.detail : nil;
+  }
+
   function domQuery(sel) {
     return _hasDom ? document.querySelector(sel) : null;
   }
@@ -2897,6 +2921,12 @@ PLATFORM_DOM_JS = """
   function domSetData(el, key, val) {
     if (el) { if (!el._sxData) el._sxData = {}; el._sxData[key] = val; }
   }
+  function domGetData(el, key) {
+    return (el && el._sxData) ? (el._sxData[key] != null ? el._sxData[key] : nil) : nil;
+  }
+  function jsonParse(s) {
+    try { return JSON.parse(s); } catch(e) { return {}; }
+  }
 
   // =========================================================================
   // Performance overrides — replace transpiled spec with imperative JS
@@ -4142,6 +4172,8 @@ def public_api_js(has_html, has_sx, has_dom, has_engine, has_orch, has_boot, has
         api_lines.append('    renderComponent: typeof sxRenderComponent === "function" ? sxRenderComponent : null,')
         api_lines.append('    getEnv: function() { return componentEnv; },')
         api_lines.append('    resolveSuspense: typeof resolveSuspense === "function" ? resolveSuspense : null,')
+        api_lines.append('    hydrateIslands: typeof sxHydrateIslands === "function" ? sxHydrateIslands : null,')
+        api_lines.append('    disposeIsland: typeof disposeIsland === "function" ? disposeIsland : null,')
         api_lines.append('    init: typeof bootInit === "function" ? bootInit : null,')
     elif has_orch:
         api_lines.append('    init: typeof engineInit === "function" ? engineInit : null,')
@@ -4178,6 +4210,12 @@ def public_api_js(has_html, has_sx, has_dom, has_engine, has_orch, has_boot, has
         api_lines.append('    batch: batch,')
         api_lines.append('    isSignal: isSignal,')
         api_lines.append('    makeSignal: makeSignal,')
+        api_lines.append('    defStore: defStore,')
+        api_lines.append('    useStore: useStore,')
+        api_lines.append('    clearStores: clearStores,')
+        api_lines.append('    emitEvent: emitEvent,')
+        api_lines.append('    onEvent: onEvent,')
+        api_lines.append('    bridgeEvent: bridgeEvent,')
     api_lines.append(f'    _version: "{version}"')
     api_lines.append('  };')
     api_lines.append('')