feat(config): resolve the API base at runtime from config.js

public/config.js

@@ -0,0 +1,30 @@
+/*
+ * Runtime configuration — edited on the server, not baked into the bundle.
+ *
+ * Vite inlines import.meta.env.VITE_* at build time, so a bundle built for one
+ * backend URL cannot be pointed at another without rebuilding. That is the wrong
+ * shape for a deployment where the backend goes up first and the UI follows, or
+ * where the same artifact is promoted from demo to staging. This file is served
+ * from the static root unbundled, so ops can change the API base and reload.
+ *
+ * Precedence, highest first:
+ *   1. apiBaseUrl below, if it is a non-empty string
+ *   2. VITE_UDYAM_API_BASE_URL, compiled in at build time
+ *   3. "/api/v1/udyam" — same-origin, which is what the nginx and httpd configs
+ *      in DEPLOYMENT.md set up
+ *
+ * Leave it empty for a same-origin deployment; that is the common case and needs
+ * no edit. Set it when the API lives on another host:
+ *
+ *   apiBaseUrl: "https://udyamlinc-api.lincpay.tech/api/v1/udyam"
+ *
+ * A cross-origin value also needs that origin in the backend's
+ * UDYAM_CORS_ALLOWED_ORIGINS, or the browser blocks every call while the API
+ * itself looks healthy.
+ *
+ * This file must never be cached — the server configs send no-store for it.
+ * Cached, it silently pins the old URL for anyone who has already loaded the app.
+ */
+window.__UDYAM_CONFIG__ = {
+  apiBaseUrl: '',
+}