build: Change to use esbuild.

- Drop esm as cosmiconfig doesn't support it anyway.

Author: Codex-

.eslintrc.json

@@ -6,6 +6,7 @@
   },
   "ignorePatterns": [
     "lib/__fixtures__/**/*.ts",
+    "esbuild.config.mjs",
     "jest.config.ts",
     "coverage",
     "dist"

esbuild.config.mjs

@@ -0,0 +1,54 @@
+import chalk from "chalk";
+import { analyzeMetafile, build } from "esbuild";
+import { readFile } from "fs/promises";
+import path from "path";
+import { fileURLToPath } from "url";
+
+const nodeTargets = ["node14", "node16", "node18"];
+
+const __dirname = path.dirname(fileURLToPath(import.meta.url));
+const packageJsonPath = path.resolve(__dirname, "package.json");
+
+async function getExternals() {
+  const packageJson = JSON.parse(await readFile(packageJsonPath));
+
+  return Object.keys(packageJson.peerDependencies);
+}
+
+(async () => {
+  try {
+    const startTime = Date.now();
+    console.info(
+      chalk.bold(
+        `🚀 ${chalk.blueBright("cosmiconfig-typescript-loader")} Build\n`
+      )
+    );
+
+    const externalDeps = await getExternals();
+
+    const result = await build({
+      entryPoints: ["./lib/index.ts"],
+      outfile: "dist/cjs/index.js",
+      metafile: true,
+      bundle: true,
+      format: "cjs",
+      external: externalDeps,
+      platform: "node",
+      target: nodeTargets,
+      treeShaking: true,
+    });
+
+    const analysis = await analyzeMetafile(result.metafile);
+    console.info(`📝 Bundle Analysis:${analysis}`);
+
+    console.info(
+      `${chalk.bold.green("✔ Bundled successfully!")} (${
+        Date.now() - startTime
+      }ms)`
+    );
+  } catch (error) {
+    console.error(`🧨 ${chalk.red.bold("Failed:")} ${error.message}`);
+    console.debug(`📚 ${chalk.blueBright.bold("Stack:")} ${error.stack}`);
+    process.exit(1);
+  }
+})();