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/ToastStack.vue

@@ -0,0 +1,66 @@
+<template>
+  <Teleport to="body">
+    <div class="fixed top-4 right-4 z-[9999] flex flex-col gap-2 pointer-events-none max-w-sm w-full">
+      <TransitionGroup name="toast-stack">
+        <div
+          v-for="toast in toasts"
+          :key="toast.id"
+          class="toast-stack-item pointer-events-auto flex items-center gap-3 px-4 py-3 rounded-xl border cursor-pointer"
+          :class="variantClass(toast.variant)"
+          @click="dismiss(toast.id)"
+        >
+          <div class="w-5 h-5 shrink-0 flex items-center justify-center">
+            <!-- Success -->
+            <svg v-if="toast.variant === 'success'" class="w-5 h-5 text-green-400" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+              <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M5 13l4 4L19 7" />
+            </svg>
+            <!-- Error -->
+            <svg v-else-if="toast.variant === 'error'" class="w-5 h-5 text-red-400" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+              <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M6 18L18 6M6 6l12 12" />
+            </svg>
+            <!-- Info -->
+            <svg v-else class="w-5 h-5 text-blue-400" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+              <path stroke-linecap="round" stroke-linejoin="round" stroke-width="2" d="M13 16h-1v-4h-1m1-4h.01M21 12a9 9 0 11-18 0 9 9 0 0118 0z" />
+            </svg>
+          </div>
+          <span class="text-sm text-white/90 flex-1">{{ toast.message }}</span>
+        </div>
+      </TransitionGroup>
+    </div>
+  </Teleport>
+</template>
+
+<script setup lang="ts">
+import { useToast } from '@/composables/useToast'
+import type { ToastVariant } from '@/composables/useToast'
+
+const { toasts, dismiss } = useToast()
+
+function variantClass(variant: ToastVariant): string {
+  switch (variant) {
+    case 'success': return 'bg-black/70 border-green-500/30 backdrop-blur-md'
+    case 'error': return 'bg-black/70 border-red-500/30 backdrop-blur-md'
+    default: return 'bg-black/70 border-blue-500/30 backdrop-blur-md'
+  }
+}
+</script>
+
+<style scoped>
+.toast-stack-enter-active {
+  transition: opacity 0.3s ease, transform 0.3s cubic-bezier(0.4, 0, 0.2, 1);
+}
+.toast-stack-leave-active {
+  transition: opacity 0.2s ease, transform 0.2s ease;
+}
+.toast-stack-enter-from {
+  opacity: 0;
+  transform: translateX(100%);
+}
+.toast-stack-leave-to {
+  opacity: 0;
+  transform: translateX(50%);
+}
+.toast-stack-move {
+  transition: transform 0.3s ease;
+}
+</style>