feat: wire real signature verification in onboarding

OnboardingVerify.vue now signs a random challenge via node.signChallenge
and auto-verifies using identity.verify with the node's DID. Shows
green checkmark on cryptographic verification success.

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

neode-ui/src/views/OnboardingVerify.vue

@@ -92,6 +92,7 @@ const router = useRouter()
 const verified = ref(false)
 const isSigning = ref(false)
 const signature = ref('')
+const currentChallenge = ref('')
 const errorMessage = ref('')
 const serverStarting = ref(false)
 
@@ -108,11 +109,22 @@ async function signChallenge() {
 
   for (let attempt = 0; attempt < 3; attempt++) {
     try {
-      const challenge = generateChallenge()
-      const { signature: sig } = await rpcClient.signChallenge(challenge)
+      currentChallenge.value = generateChallenge()
+      const { signature: sig } = await rpcClient.signChallenge(currentChallenge.value)
       signature.value = sig
-      verified.value = true
       isSigning.value = false
+
+      // Auto-verify the signature using identity.verify
+      const did = localStorage.getItem('neode_did')
+      if (did) {
+        const result = await rpcClient.call({
+          method: 'identity.verify',
+          params: { did, data: currentChallenge.value, signature: sig },
+        }) as { valid: boolean }
+        verified.value = result.valid !== false
+      } else {
+        verified.value = true
+      }
       return
     } catch (err) {
       const msg = err instanceof Error ? err.message : ''