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/components/RouteTable.vue

@@ -0,0 +1,58 @@
+<script setup lang="ts">
+import type { Metric, Route } from "@/lib/api";
+
+defineProps<{
+  rows: Route[];
+  ready: boolean;
+}>();
+
+function metricLabel(m: Metric): string {
+  return typeof m === "number" ? String(m) : m;
+}
+
+function metricClass(m: Metric): string {
+  if (typeof m === "number") {
+    if (m === 0) return "text-emerald-500";
+    if (m < 10) return "text-foreground";
+    return "text-yellow-500";
+  }
+  return "text-destructive";
+}
+
+function rowKey(r: Route): string {
+  return `${r.subnet}|${r.nextHop}|${r.seqno}`;
+}
+</script>
+
+<template>
+  <div class="overflow-hidden rounded-lg border border-border">
+    <table class="w-full text-sm">
+      <thead class="bg-muted/40 text-xs uppercase text-muted-foreground">
+        <tr>
+          <th class="px-4 py-2 text-left font-medium">Subnet</th>
+          <th class="px-4 py-2 text-left font-medium">Next hop</th>
+          <th class="px-4 py-2 text-right font-medium">Metric</th>
+          <th class="px-4 py-2 text-right font-medium">Seqno</th>
+        </tr>
+      </thead>
+      <tbody class="divide-y divide-border">
+        <tr v-if="!rows.length">
+          <td colspan="4" class="px-4 py-8 text-center text-muted-foreground">
+            {{ ready ? "No routes." : "Daemon offline." }}
+          </td>
+        </tr>
+        <tr v-for="r in rows" :key="rowKey(r)" class="hover:bg-muted/30">
+          <td class="px-4 py-2 font-mono text-xs break-all">{{ r.subnet }}</td>
+          <td class="px-4 py-2 font-mono text-xs break-all">{{ r.nextHop }}</td>
+          <td
+            class="px-4 py-2 text-right font-mono text-xs"
+            :class="metricClass(r.metric)"
+          >
+            {{ metricLabel(r.metric) }}
+          </td>
+          <td class="px-4 py-2 text-right font-mono text-xs">{{ r.seqno }}</td>
+        </tr>
+      </tbody>
+    </table>
+  </div>
+</template>