fix: standardize inline script transpilation in tsup config

Use stdin-based esbuild.build with proper TS transpilation, minification,
and ESM output format matching v5's proven inline-script-loader pattern.

tsup.config.ts

@@ -1,5 +1,47 @@
 import { defineConfig } from "tsup";
-import * as esbuild from "esbuild";
+import type { Plugin } from "esbuild";
+import path from "path";
+
+const inlineScriptPlugin: Plugin = {
+  name: "inline-script-loader",
+  setup(parentBuild) {
+    const absWorkingDir = parentBuild.initialOptions.absWorkingDir ?? process.cwd();
+
+    parentBuild.onLoad({ filter: /\.scss$/ }, async (args) => {
+      const fs = await import("fs");
+      const text = await fs.promises.readFile(args.path, "utf8");
+      return { contents: text, loader: "text" };
+    });
+
+    parentBuild.onLoad({ filter: /\.inline\.ts$/ }, async (args) => {
+      const esbuild = await import("esbuild");
+      const fs = await import("fs");
+      let text = await fs.promises.readFile(args.path, "utf8");
+      text = text.replace(/^export default /gm, "");
+      text = text.replace(/^export /gm, "");
+
+      const resolveDir = path.dirname(args.path);
+      const sourcefile = path.relative(absWorkingDir, args.path);
+
+      const result = await esbuild.build({
+        stdin: { contents: text, loader: "ts", resolveDir, sourcefile },
+        write: false,
+        bundle: true,
+        minify: true,
+        platform: "browser",
+        format: "esm",
+        target: "es2020",
+        sourcemap: false,
+        external: ["http://*", "https://*"],
+      });
+
+      const js = result.outputFiles?.[0]?.text;
+      if (!js) throw new Error(`inline-script-loader: no JS output for ${args.path}`);
+
+      return { contents: js, loader: "text" };
+    });
+  },
+};
 
 export default defineConfig({
   entry: {
@@ -19,36 +61,5 @@ export default defineConfig({
     options.jsx = "automatic";
     options.jsxImportSource = "preact";
   },
-  esbuildPlugins: [
-    {
-      name: "text-loader",
-      setup(build) {
-        build.onLoad({ filter: /\.scss$/ }, async (args) => {
-          const fs = await import("fs");
-          const text = await fs.promises.readFile(args.path, "utf8");
-          return {
-            contents: text,
-            loader: "text",
-          };
-        });
-
-        build.onLoad({ filter: /\.inline\.ts$/ }, async (args) => {
-          const result = await esbuild.build({
-            entryPoints: [args.path],
-            bundle: true,
-            write: false,
-            format: "iife",
-            target: "es2022",
-            minify: false,
-            platform: "browser",
-          });
-          const code = result.outputFiles?.[0]?.text ?? "";
-          return {
-            contents: `export default ${JSON.stringify(code)};`,
-            loader: "ts",
-          };
-        });
-      },
-    },
-  ],
+  esbuildPlugins: [inlineScriptPlugin],
 });