Add SQLite message and peer persistence (internal/store)

Each daemon writes to <data-dir>/messages.db on startup. Messages received
or sent are stored immediately; duplicate mids (INSERT OR IGNORE) are safe
to call multiple times. Peer aliases are upserted on peer_connected and
again after hello verification when the real nick is known.

Schema
- messages(mid UNIQUE, room, from_peer, body, sent_at) — mid is the YAW/2
  dedup key added in the proto migration; index on (room, sent_at) for
  efficient per-room queries.
- peers(peer_id PK, alias, last_seen) — cache of every peer ever seen,
  used to resolve hex ids to names when peers are offline.

Wiring
- store.Open called in cmd/daemon/main.go, passed to mesh.New.
- mesh.Mesh holds *store.Store (nil-safe; persistence is optional).
- mesh.SaveMessage called in dispatchPeerMessage (incoming) and ipc
  CmdSendMessage (outgoing) so the local node's own messages are stored.
- mesh.UpdatePeerAlias called after hello verification updates the alias
  with the verified nick rather than the placeholder short-id.

Messages only accumulate from join time forward — no history replay to
late-joining peers; each node's view starts from when it connected.

test-network.sh: added SQLite verification block that queries each node's
DB after the test and prints message + peer counts.

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

internal/mesh/mesh.go

@@ -2,10 +2,12 @@
 package mesh
 
 import (
+	"log"
 	"sync"
 
 	"github.com/waste-go/internal/crypto"
 	"github.com/waste-go/internal/proto"
+	"github.com/waste-go/internal/store"
 )
 
 // PeerConn is a live connection to one peer.
@@ -19,9 +21,10 @@ type PeerConn struct {
 // All methods are safe to call from multiple goroutines.
 type Mesh struct {
 	Identity *crypto.Identity
+	Store    *store.Store // may be nil if persistence is disabled
 
-	mu       sync.RWMutex
-	peers    map[proto.PeerID]*PeerConn
+	mu    sync.RWMutex
+	peers map[proto.PeerID]*PeerConn
 
 	// subscribers receive a copy of every event (fan-out to IPC clients)
 	subMu sync.Mutex
@@ -29,9 +32,11 @@ type Mesh struct {
 }
 
 // New creates an empty mesh with the given identity.
-func New(id *crypto.Identity) *Mesh {
+// Pass a non-nil store to enable message and peer persistence.
+func New(id *crypto.Identity, st *store.Store) *Mesh {
 	return &Mesh{
 		Identity: id,
+		Store:    st,
 		peers:    make(map[proto.PeerID]*PeerConn),
 	}
 }
@@ -44,12 +49,38 @@ func (m *Mesh) AddPeer(conn *PeerConn) {
 	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,
 	})
 }
 
+// SaveMessage persists a chat message if a store is configured.
+// Duplicate mids are silently dropped.
+func (m *Mesh) SaveMessage(msg *proto.ChatMessage) {
+	if m.Store == nil || msg == nil {
+		return
+	}
+	if err := m.Store.SaveMessage(msg); err != nil {
+		log.Printf("mesh: store message %s: %v", msg.Mid, err)
+	}
+}
+
+// UpdatePeerAlias updates the cached alias for a peer after hello verification.
+func (m *Mesh) UpdatePeerAlias(id proto.PeerID, alias string) {
+	if m.Store != nil && alias != "" {
+		if err := m.Store.SavePeer(id, alias); err != nil {
+			log.Printf("mesh: update peer alias %s: %v", id.Short(), err)
+		}
+	}
+}
+
 // RemovePeer unregisters a peer and notifies subscribers.
 func (m *Mesh) RemovePeer(id proto.PeerID) {
 	m.mu.Lock()

internal/mesh/peer.go

@@ -128,6 +128,7 @@ func handleDCMessage(data []byte, from proto.PeerID, localID *crypto.Identity, m
 			conn.Info.PublicKey = hello.ID
 		}
 		m.mu.Unlock()
+		m.UpdatePeerAlias(from, hello.Nick)
 		m.Emit(proto.IpcMessage{
 			Type:   proto.EvtSessionReady,
 			PeerID: peerIDPtr(from),
@@ -148,6 +149,7 @@ func dispatchPeerMessage(msg proto.PeerMessage, from proto.PeerID, m *Mesh) {
 	switch msg.Type {
 	case proto.MsgChat:
 		if msg.Chat != nil {
+			m.SaveMessage(msg.Chat)
 			m.Emit(proto.IpcMessage{Type: proto.EvtMessageReceived, Message: msg.Chat})
 		}
 	case proto.MsgPeerGossip: