feat: initial OmniRoute release (rebranded from 9router)

This project is inspired by and originally forked from 9router by decolua
(https://github.com/decolua/9router).

Full rebrand: 9router → OmniRoute across all source code, configuration,
Docker, documentation, and assets.

src/shared/utils/upstreamError.js

@@ -0,0 +1,52 @@
+/**
+ * Normalize upstream error bodies to a JSON-safe payload.
+ * Accepts unknown/object/string inputs and guarantees an { error: { ... } } shape.
+ */
+export function toJsonErrorPayload(rawError, fallbackMessage = "Upstream provider error") {
+  const fallback = {
+    error: {
+      message: fallbackMessage,
+      type: "upstream_error",
+      code: "upstream_error",
+    },
+  };
+
+  if (rawError && typeof rawError === "object") {
+    const errorObj = rawError.error;
+    if (typeof errorObj === "string") {
+      return {
+        error: {
+          message: errorObj,
+          type: "upstream_error",
+          code: "upstream_error",
+        },
+      };
+    }
+    if (errorObj && typeof errorObj === "object") {
+      return rawError;
+    }
+    return { error: rawError };
+  }
+
+  if (typeof rawError === "string") {
+    const trimmed = rawError.trim();
+    if (!trimmed) {
+      return fallback;
+    }
+
+    try {
+      const parsed = JSON.parse(trimmed);
+      return toJsonErrorPayload(parsed, fallbackMessage);
+    } catch {
+      return {
+        error: {
+          message: trimmed,
+          type: "upstream_error",
+          code: "upstream_error",
+        },
+      };
+    }
+  }
+
+  return fallback;
+}