test(m3): add Upstash read-tier rate limit HTTP test

Node test asserts 429 with Retry-After after 60 GET requests per IP.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/test-support/load-env-local.ts

@@ -0,0 +1,35 @@
+import { existsSync, readFileSync } from "node:fs";
+import { join } from "node:path";
+
+/** Loads `.env.local` without overriding variables already set in the shell. */
+export function loadEnvLocal(): void {
+  const file = join(process.cwd(), ".env.local");
+  if (!existsSync(file)) {
+    return;
+  }
+
+  for (const line of readFileSync(file, "utf8").split(/\r?\n/)) {
+    const trimmed = line.trim();
+    if (!trimmed || trimmed.startsWith("#")) {
+      continue;
+    }
+
+    const eq = trimmed.indexOf("=");
+    if (eq <= 0) {
+      continue;
+    }
+
+    const key = trimmed.slice(0, eq).trim();
+    let value = trimmed.slice(eq + 1).trim();
+    if (
+      (value.startsWith('"') && value.endsWith('"')) ||
+      (value.startsWith("'") && value.endsWith("'"))
+    ) {
+      value = value.slice(1, -1);
+    }
+
+    if (process.env[key] === undefined) {
+      process.env[key] = value;
+    }
+  }
+}