runtime + codegen-js: Promise helpers and object/array utilities

Add to el_runtime.js:
  promise_then(p, cb)    -- p.then(cb), works with any Promise-returning API
  promise_catch(p, cb)   -- p.catch(cb)
  promise_resolve(val)   -- Promise.resolve(val)
  promise_reject(msg)    -- Promise.reject(new Error(msg))
  object_assign(t, s)    -- Object.assign({}, t, s) (non-mutating)
  object_keys(obj)       -- Object.keys(obj)
  object_values(obj)     -- Object.values(obj)
  json_deep_clone(obj)   -- JSON.parse(JSON.stringify(obj))
  array_from(iterable)   -- Array.from(iterable)
  type_of(val)           -- typeof val
  instanceof_check(v, n) -- val instanceof globalThis[name]

All new functions added to __el export object and ES named exports.
codegen-js preamble destructure updated to include all new names.

el-compiler/runtime/el_runtime.js

@@ -766,6 +766,68 @@ function window_get(name) {
     return null;
 }
 
+// ── Promise helpers ────────────────────────────────────────────────────────
+//
+// Third-party APIs often return Promises but are not El @async functions.
+// These helpers let El programs chain .then / .catch without needing
+// native_js, and without requiring the callee to be @async.
+
+function promise_then(p, cb) {
+    return Promise.resolve(p).then(cb);
+}
+
+function promise_catch(p, cb) {
+    return Promise.resolve(p).catch(cb);
+}
+
+function promise_resolve(val) {
+    return Promise.resolve(val);
+}
+
+function promise_reject(msg) {
+    return Promise.reject(new Error(String(msg)));
+}
+
+// ── Object / Array utilities ───────────────────────────────────────────────
+//
+// Structural operations on Any-typed JS values. These complement the
+// El map/list primitives for interop with third-party library objects.
+
+function object_assign(target, source) {
+    return Object.assign(Object.assign({}, target), source);
+}
+
+function object_keys(obj) {
+    if (obj === null || obj === undefined) return [];
+    return Object.keys(obj);
+}
+
+function object_values(obj) {
+    if (obj === null || obj === undefined) return [];
+    return Object.values(obj);
+}
+
+function json_deep_clone(obj) {
+    if (obj === null || obj === undefined) return null;
+    return JSON.parse(JSON.stringify(obj));
+}
+
+function array_from(iterable) {
+    if (iterable === null || iterable === undefined) return [];
+    return Array.from(iterable);
+}
+
+function type_of(val) {
+    return typeof val;
+}
+
+function instanceof_check(val, constructor_name) {
+    if (typeof globalThis[constructor_name] === 'function') {
+        return val instanceof globalThis[constructor_name];
+    }
+    return false;
+}
+
 // ── native_js escape hatch ─────────────────────────────────────────────────
 //
 // Evaluate arbitrary JS from El source. Intended for calling third-party
@@ -910,6 +972,11 @@ const __el = {
     console_log,
     // Window export helpers
     window_set, window_get,
+    // Promise helpers
+    promise_then, promise_catch, promise_resolve, promise_reject,
+    // Object / Array utilities
+    object_assign, object_keys, object_values, json_deep_clone,
+    array_from, type_of, instanceof_check,
     // native_js escape hatch
     native_js, native_js_call,
     // CGI / DHARMA / Engram / LLM (stubs)
@@ -974,4 +1041,9 @@ export {
     console_log,
     // Window / native_js
     window_set, window_get, native_js, native_js_call,
+    // Promise helpers
+    promise_then, promise_catch, promise_resolve, promise_reject,
+    // Object / Array utilities
+    object_assign, object_keys, object_values, json_deep_clone,
+    array_from, type_of, instanceof_check,
 };