Fix web UI messaging, alias resolution, and onboarding

Messaging:
- Append \n to WS IPC sends so bufio.Scanner fires (messages from web
  were silently dropped — the line scanner never saw a newline)
- Handle session_ready in web store to update peer aliases after hello

Alias resolution:
- Seed AddPeer alias from SQLite cache so returning peers resolve
  immediately, before hello exchange completes
- Remove stale SavePeer call from AddPeer (was writing placeholder IDs)
- Add PeerAlias() point-lookup to store

Onboarding redesign:
- Three-state UI: disconnected (daemon instructions), connecting,
  connected-no-network (join form)
- Read ?n= / ?network= / ?anchor= / ?invite=waste:... URL params to
  pre-fill the join form for invite links
- Show daemon alias + peer ID before any network is joined
  (master_alias + master_id now included in state_snapshot)
- Identity backup: export (passphrase-protected yaw-key-backup-1 JSON,
  download button) and restore (paste + passphrase verify)

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

internal/mesh/mesh.go

@@ -89,16 +89,17 @@ func (m *Mesh) ScanShareDir() []proto.FileEntry {
 
 // AddPeer registers a connected peer and notifies subscribers.
 func (m *Mesh) AddPeer(conn *PeerConn) {
+	// Seed alias from cache so returning peers resolve immediately (before hello).
+	if m.Store != nil {
+		if cached := m.Store.PeerAlias(conn.Info.ID); cached != "" {
+			conn.Info.Alias = cached
+		}
+	}
+
 	m.mu.Lock()
 	m.peers[conn.Info.ID] = conn
 	m.mu.Unlock()
 
-	if m.Store != nil && conn.Info.Alias != "" {
-		if err := m.Store.SavePeer(conn.Info.ID, conn.Info.Alias); err != nil {
-			log.Printf("mesh: store peer %s: %v", conn.Info.ID.Short(), err)
-		}
-	}
-
 	m.emit(proto.IpcMessage{
 		Type: proto.EvtPeerConnected,
 		Peer: &conn.Info,