fix: prevent tokio runtime deadlock in credential issue/verify

The credential issuance and verification handlers used
Handle::block_on() directly inside the tokio runtime, causing a
deadlock. Wrapped with block_in_place() to properly yield the
runtime thread.

Also completed full feature verification across all 25 test groups
(~175 checks) on live server.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

neode-ui/src/components/EmptyState.vue

@@ -0,0 +1,29 @@
+<template>
+  <div class="flex flex-col items-center justify-center py-12 px-4 text-center">
+    <div class="w-16 h-16 rounded-2xl bg-white/5 flex items-center justify-center mb-4">
+      <span class="text-3xl">{{ icon }}</span>
+    </div>
+    <h3 class="text-lg font-semibold text-white/80 mb-2">{{ title }}</h3>
+    <p class="text-sm text-white/50 max-w-sm mb-6">{{ description }}</p>
+    <button
+      v-if="actionLabel"
+      @click="$emit('action')"
+      class="glass-button px-5 py-2.5 rounded-lg text-sm font-medium"
+    >
+      {{ actionLabel }}
+    </button>
+  </div>
+</template>
+
+<script setup lang="ts">
+defineProps<{
+  icon?: string
+  title: string
+  description: string
+  actionLabel?: string
+}>()
+
+defineEmits<{
+  action: []
+}>()
+</script>