feat: initial miq.stats-plugin implementation

Operating-numbers view plugin (MIQ-1734): per-agent load, in-flight
per project, pending-decision age, 7-day throughput, and budget tile.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

vitest.config.ts

@@ -0,0 +1,8 @@
+import { defineConfig } from "vitest/config";
+
+export default defineConfig({
+  test: {
+    environment: "jsdom",
+    globals: true,
+  },
+});