feat(toast): message toast opens the related chat + has a close icon (#33)

- Add a close (X) button to the message toast (closeToast, @click.stop) like the
  system notifications.
- Carry the sender pubkey on the toast; clicking now deep-links to that
  conversation (/dashboard/mesh?peer=<pubkey>) instead of the generic mesh page.
- Mesh.vue reads ?peer= on mount and opens the matching peer (by pubkey_hex/did),
  gracefully falling back to the mesh list when no match (B1/B2 identity).

type-check clean; useMessageToast tests 11/11.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

neode-ui/src/views/Mesh.vue

@@ -1,5 +1,6 @@
 <script setup lang="ts">
 import { ref, computed, watch, nextTick, onMounted, onUnmounted } from 'vue'
+import { useRoute } from 'vue-router'
 import { useMeshStore } from '@/stores/mesh'
 import { useTransportStore } from '@/stores/transport'
 import type { MeshMessage, MeshPeer, SessionStatus } from '@/stores/mesh'
@@ -12,6 +13,7 @@ import '@/views/mesh/mesh-styles.css'
 
 const mesh = useMeshStore()
 const transport = useTransportStore()
+const route = useRoute()
 
 // Responsive layout breakpoints
 const isWideDesktop = ref(window.innerWidth >= 1536)
@@ -301,6 +303,15 @@ onMounted(async () => {
   loadPendingFromSession()
   await Promise.all([mesh.refreshAll(), transport.fetchStatus(), refreshFederationNodes(), refreshSelfOnion(), refreshSelfDid(), refreshContacts()])
   refreshOutboxCount()
+  // Deep-link from a message toast: open the sender's conversation if we can
+  // match it; otherwise just land on the mesh page (graceful fallback).
+  const targetPeer = typeof route.query.peer === 'string' ? route.query.peer : ''
+  if (targetPeer) {
+    const match = mesh.peers.find(
+      (p) => p.pubkey_hex === targetPeer || p.did === targetPeer
+    )
+    if (match) openChat(match)
+  }
   // Start background polling for Archipelago (Tor) messages so unread count works
   loadArchMessages()
   if (!archPollInterval) {