fix: compact timestamps, historical alias resolution, wider ts column

- Timestamps now show "Jun 28 10:58" for older messages (dropped
  "Yesterday" which overflowed the fixed-width column)
- Timestamp column widened from 52px to 72px to fit date+time
- state_snapshot now includes known_peers (historically seen, not
  currently connected) so the UI can resolve aliases in history
- MessagePane aliasFor falls back to knownPeers map

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

internal/proto/proto.go

@@ -350,6 +350,7 @@ type IpcMessage struct {
 	MasterID       string        `json:"master_id,omitempty"`    // daemon's master public key hex
 	LocalPeer      *PeerInfo     `json:"local_peer,omitempty"`
 	ConnectedPeers []PeerInfo    `json:"connected_peers,omitempty"`
+	KnownPeers     []PeerInfo    `json:"known_peers,omitempty"` // historically seen, not currently connected
 	Rooms          []string      `json:"rooms,omitempty"`
 	// multi-network: all joined networks (additive)
 	Networks       []NetworkInfo `json:"networks,omitempty"`