fix(packages): resolve npm bin entrypoint detection (#567)

Fix npm/global bin entrypoint detection for CLI and MCP server by normalizing real entry paths, including symlinked invocations.

packages/node-core/tests/entrypoint.test.ts

@@ -0,0 +1,48 @@
+import assert from "node:assert/strict";
+import { mkdir, mkdtemp, rm, symlink, writeFile } from "node:fs/promises";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { pathToFileURL } from "node:url";
+import test from "node:test";
+import { isMainModule } from "../src/entrypoint.js";
+
+test("matches a module invoked through its real file path", async () => {
+  const dir = await mkdtemp(join(tmpdir(), "dbx-entrypoint-"));
+  try {
+    const entry = join(dir, "cli.js");
+    await writeFile(entry, "", "utf-8");
+
+    assert.equal(isMainModule(pathToFileURL(entry).href, entry), true);
+  } finally {
+    await rm(dir, { recursive: true, force: true });
+  }
+});
+
+test("matches a module invoked through an npm-style symlink", async () => {
+  const dir = await mkdtemp(join(tmpdir(), "dbx-entrypoint-"));
+  try {
+    const entry = join(dir, "dist", "cli.js");
+    const bin = join(dir, "dbx");
+    await mkdir(join(dir, "dist"));
+    await writeFile(entry, "", "utf-8");
+    await symlink(entry, bin);
+
+    assert.equal(isMainModule(pathToFileURL(entry).href, bin), true);
+  } finally {
+    await rm(dir, { recursive: true, force: true });
+  }
+});
+
+test("does not match a different entry file", async () => {
+  const dir = await mkdtemp(join(tmpdir(), "dbx-entrypoint-"));
+  try {
+    const entry = join(dir, "cli.js");
+    const other = join(dir, "other.js");
+    await writeFile(entry, "", "utf-8");
+    await writeFile(other, "", "utf-8");
+
+    assert.equal(isMainModule(pathToFileURL(entry).href, other), false);
+  } finally {
+    await rm(dir, { recursive: true, force: true });
+  }
+});