Add native self-hosted instance connection to fluxer_desktop

Trimmed monorepo checkout (fluxer_desktop + packages/voice_engine_v2 +
tools/ci) with a "Connect to a Different Server" menu item and popout
that lets the desktop app switch to any self-hosted Fluxer instance,
plus fixes for well-known discovery on single-domain self-hosted
deployments and a false-positive ERR_ABORTED on same-origin client
redirects during the switch. Defaults to chat.fluxr.chat and uses an
isolated userData directory from the official build.

fluxer_desktop/native/webauthn/vm_tests/vfido_authenticator/main.go

@@ -0,0 +1,89 @@
+package main
+
+import (
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"crypto/rand"
+	"crypto/sha256"
+	"crypto/x509"
+	"crypto/x509/pkix"
+	"fmt"
+	"io"
+	"math/big"
+	"os"
+	"time"
+
+	virtual_fido "github.com/bulwarkid/virtual-fido"
+	"github.com/bulwarkid/virtual-fido/fido_client"
+)
+
+type autoApproveSupport struct {
+	vaultFilename string
+}
+
+func (support *autoApproveSupport) ApproveClientAction(action fido_client.ClientAction, params fido_client.ClientActionRequestParams) bool {
+	fmt.Printf("auto-approving action=%d relyingParty=%q user=%q\n", action, params.RelyingParty, params.UserName)
+	return true
+}
+
+func (support *autoApproveSupport) SaveData(data []byte) {
+	err := os.WriteFile(support.vaultFilename, data, 0o600)
+	if err != nil {
+		panic(fmt.Sprintf("could not write vault: %s", err))
+	}
+}
+
+func (support *autoApproveSupport) RetrieveData() []byte {
+	f, err := os.Open(support.vaultFilename)
+	if os.IsNotExist(err) {
+		return nil
+	}
+	if err != nil {
+		panic(fmt.Sprintf("could not open vault: %s", err))
+	}
+	defer f.Close()
+	data, err := io.ReadAll(f)
+	if err != nil {
+		panic(fmt.Sprintf("could not read vault: %s", err))
+	}
+	return data
+}
+
+func (support *autoApproveSupport) Passphrase() string {
+	return "vm-test-passphrase"
+}
+
+func main() {
+	vault := os.Getenv("VFIDO_VAULT")
+	if vault == "" {
+		vault = "/tmp/vfido-vault.json"
+	}
+	authority := &x509.Certificate{
+		SerialNumber: big.NewInt(0),
+		Subject: pkix.Name{
+			Organization: []string{"Fluxer VM Test Virtual FIDO"},
+			Country:      []string{"US"},
+		},
+		NotBefore:             time.Now(),
+		NotAfter:              time.Now().AddDate(10, 0, 0),
+		IsCA:                  true,
+		ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageClientAuth, x509.ExtKeyUsageServerAuth},
+		KeyUsage:              x509.KeyUsageDigitalSignature | x509.KeyUsageCertSign,
+		BasicConstraintsValid: true,
+	}
+	privateKey, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	if err != nil {
+		panic(err)
+	}
+	authorityCertBytes, err := x509.CreateCertificate(rand.Reader, authority, authority, &privateKey.PublicKey, privateKey)
+	if err != nil {
+		panic(err)
+	}
+	encryptionKey := sha256.Sum256([]byte("fluxer-vm-test"))
+
+	virtual_fido.SetLogOutput(os.Stdout)
+	support := &autoApproveSupport{vaultFilename: vault}
+	client := fido_client.NewDefaultClient(authorityCertBytes, privateKey, encryptionKey, support, support)
+	fmt.Println("virtual-fido USBIP server starting on 127.0.0.1:3240 (bus 2-2)")
+	virtual_fido.Start(client)
+}