fix: don't statically resolve dist/ in packaging test (breaks CI typecheck)

The plugin-default-export packaging test imported "../dist/index.js" as a
string literal, so `tsc --noEmit` tried to resolve it — failing the typecheck
CI step, which runs before `dist/` is built. Import via a runtime URL instead;
behavior is unchanged and the file exists during `npm run test`.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: ebuildy

test/packaging.test.ts

@@ -45,7 +45,13 @@ describe("packaging: ESM-only", () => {
 
 describe("packaging: plugin default export", () => {
   it("exposes a Docusaurus plugin as the package default export", async () => {
-    const mod = await import("../dist/index.js");
+    // Import the built artifact via a runtime URL so `tsc --noEmit` doesn't try to
+    // resolve `dist/` (which isn't built during the typecheck CI step). `npm run
+    // test` builds the package first, so the file exists at runtime.
+    const entry = new URL("../dist/index.js", import.meta.url).href;
+    const mod = (await import(entry)) as {
+      default: (context: unknown, options: unknown) => { name: string };
+    };
     expect(typeof mod.default).toBe("function");
     const plugin = mod.default({}, { host: "https://gitlab.example.com", cache: false });
     expect(plugin.name).toBe("@ebuildy/docusaurus-plugin-gitlab");