fix: get env variable dynamically to avoid secret leakage

tsup.config.ts

@@ -0,0 +1,21 @@
+import { defineConfig } from "tsup";
+
+export default defineConfig({
+  entry: [
+    "src/index.ts",
+    "src/runtime.ts",
+    "src/middleware.ts",
+    "src/routes/login.ts",
+    "src/routes/callback.ts",
+    "src/routes/logout.ts",
+    "src/lib/cookies.ts",
+    "src/lib/pkce.ts",
+    "src/lib/sign.ts",
+  ],
+  format: ["esm"],
+  dts: true,
+  sourcemap: true,
+  clean: true,
+  outDir: "dist",
+  external: ["astro:env/server"],
+});