fix(widget): make the bundle importable without a DOM

The package documented itself as safe to import in Node, with registration a
no-op absent a DOM. That was false: a class declaration evaluates its extends
clause at module load, so `extends globalThis.HTMLElement` threw before
canRegisterElements() could run. Caught by loading the deployed bundle rather
than the source.

Falls back to a plain base class when there is no DOM, so a server-rendering
host can import the helpers and the documented promise is now true.

packages/widget/src/base.js

@@ -163,7 +163,19 @@ export function targetFromAttributes(element) {
  *
  * Subclasses implement `render()` and may implement `template()`.
  */
-export class GovernanceElement extends globalThis.HTMLElement {
+/**
+ * Base constructor for the elements.
+ *
+ * A class declaration evaluates its `extends` clause at module load, so
+ * `extends globalThis.HTMLElement` throws in Node before any capability guard
+ * could run — which made the "safe to import without a DOM" promise false.
+ * Falling back to a plain class keeps the module importable for a
+ * server-rendering host; registration is still a no-op there.
+ */
+const ElementBase =
+  typeof globalThis.HTMLElement === "function" ? globalThis.HTMLElement : /** @type {any} */ (class {});
+
+export class GovernanceElement extends ElementBase {
   constructor() {
     super();
     this.attachShadow({ mode: "open" });

packages/widget/src/provider.js

@@ -34,7 +34,10 @@ export function requestContext(element) {
   return detail.context;
 }
 
-export class BitGateProvider extends globalThis.HTMLElement {
+const ProviderBase =
+  typeof globalThis.HTMLElement === "function" ? globalThis.HTMLElement : /** @type {any} */ (class {});
+
+export class BitGateProvider extends ProviderBase {
   static get observedAttributes() {
     return [
       "relays",

packages/widget/test/provider.test.js

@@ -302,3 +302,13 @@ describe("signature verification posture", () => {
     expect(provider.hasAttribute("data-unverified")).toBe(true);
   });
 });
+
+describe("environment safety", () => {
+  it("keeps the documented promise that it imports without a DOM", async () => {
+    // A class declaration evaluates `extends` at module load, so this used to
+    // throw in Node before any capability guard could run.
+    const { canRegisterElements } = await import("../src/base.js");
+    expect(typeof canRegisterElements).toBe("function");
+    expect(canRegisterElements()).toBe(true); // happy-dom is present here
+  });
+});