fix(tsconnect/wasm): filter offline and unreachable drive peers

listDrivePeers only checked PeerCapabilityTaildriveSharer, which is
usually granted to a whole group or tag, so it returned most of the
tailnet including offline peers and peers with no reachable peerAPI.
Apply the same conjunction as LocalBackend.driveRemotesFromPeers.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

cmd/tsconnect/wasm/drive.go

@@ -240,10 +240,14 @@ type jsDrivePeer struct {
 	Online       *bool  `json:"online,omitempty"`
 }
 
-// listDrivePeers returns a JSON array of peers that carry
-// PeerCapabilityTaildriveSharer. Returns an empty array if the local node
-// does not have drive:access in its ACL (DriveAccessEnabled). This mirrors
-// the filtering in LocalBackend.driveRemotesFromPeers.
+// listDrivePeers returns a JSON array of peers that are online, have a
+// reachable peerAPI and carry PeerCapabilityTaildriveSharer. Returns an empty
+// array if the local node does not have drive:access in its ACL
+// (DriveAccessEnabled). This mirrors the filtering in
+// LocalBackend.driveRemotesFromPeers.
+//
+// The cap means a peer is allowed to share with us, not that it currently
+// exposes any share, so the result is a superset of the peers with shares.
 func (i *jsIPN) listDrivePeers() js.Value {
 	return makePromise(func() (any, error) {
 		if !i.lb.DriveAccessEnabled() {
@@ -269,6 +273,13 @@ func (i *jsIPN) listDrivePeers() js.Value {
 
 		peers := make([]jsDrivePeer, 0)
 		for _, p := range nm.Peers {
+			if !p.Online().Get() {
+				continue
+			}
+			peerURL := buildPeerAPIURL(p, selfHave4, selfHave6)
+			if peerURL == "" {
+				continue
+			}
 			// Check PeerCapabilityTaildriveSharer via the live PeerCaps map
 			// (derived from ACL rules), mirroring driveRemotesFromPeers.
 			hasCap := false
@@ -281,7 +292,6 @@ func (i *jsIPN) listDrivePeers() js.Value {
 			if !hasCap {
 				continue
 			}
-			peerURL := buildPeerAPIURL(p, selfHave4, selfHave6)
 			online := p.Online().Clone()
 			peers = append(peers, jsDrivePeer{
 				Name:         p.DisplayName(false),