Initial Planlink implementation

server/src/config/env.js

@@ -0,0 +1,12 @@
+const dotenv = require("dotenv");
+
+dotenv.config();
+
+const required = ["JWT_SECRET"]; // Extend when wiring auth
+
+for (const key of required) {
+  if (!process.env[key]) {
+    // Keep a warning for now; enforce later when auth is wired
+    console.warn(`[env] Missing ${key}`);
+  }
+}