P3: routes (selected, fallback, queried)

Backend
- api/routes.rs models the Babel-style route shape; metric uses an
  untagged enum to round-trip both numeric hop counts and the
  literal "infinite" string the daemon emits for poisoned routes
- routes_snapshot() runs the three GETs concurrently with try_join
  so the snapshot is internally consistent
- poller spawns a second 5s loop emitting routes://updated; both
  loops are owned by the Poller and aborted together on stop_daemon

Frontend
- routes store mirrors the snapshot shape; tabbed view (radix-vue)
  with selected, fallback and queried lists
- RouteTable component shared by selected/fallback; metric column
  is colour-coded (0 green, low neutral, high yellow, infinite red)
- Queried subnets show a live `expires in 12s` countdown driven by
  a 1Hz tick ref instead of mutating the store

src/stores/routes.ts

@@ -0,0 +1,43 @@
+import { defineStore } from "pinia";
+import { ref } from "vue";
+import { api, type RoutesSnapshot } from "@/lib/api";
+import { Events, on } from "@/lib/events";
+
+export const useRoutesStore = defineStore("routes", () => {
+  const snapshot = ref<RoutesSnapshot>({
+    selected: [],
+    fallback: [],
+    queried: [],
+  });
+  const loading = ref(false);
+  const error = ref<string | null>(null);
+
+  let unlisten: (() => void) | null = null;
+
+  async function bootstrap() {
+    if (!unlisten) {
+      unlisten = await on<RoutesSnapshot>(Events.RoutesUpdated, (e) => {
+        snapshot.value = e.payload;
+      });
+    }
+  }
+
+  async function refresh() {
+    loading.value = true;
+    error.value = null;
+    try {
+      snapshot.value = await api.routesSnapshot();
+    } catch (e) {
+      error.value = String(e);
+    } finally {
+      loading.value = false;
+    }
+  }
+
+  function dispose() {
+    unlisten?.();
+    unlisten = null;
+  }
+
+  return { snapshot, loading, error, bootstrap, refresh, dispose };
+});