feat(windows): WireGuard client, auto-VPN, IAM, tray enrichment, installer, CI

Second milestone of the Windows parity work (DESIGN-WINDOWS.md §13).

WireGuard mesh client (signed, WSS-delivered):
- wireguard_apply / wireguard_remove commands: Ed25519-verified, gated on a new
  wireguard capability. Linux applies via wg-quick up/down; Windows installs the
  peer config as a WireGuardTunnel service via wireguard.exe
  (/installtunnelservice, /uninstalltunnelservice)
- state polling in the home monitor drives the blue tray icon and auto-VPN:
  connect when away from home + auto_vpn, disconnect on return (2m cooldown)
- tray VPN toggle and the auto-VPN checkbox are now live; the preference
  persists to agent.yml (PersistAutoVPN)

IAM on Windows (iam_windows.go):
- allowed_login_groups -> net localgroup; ssh_keys -> per-profile
  authorized_keys + %ProgramData%\ssh\administrators_authorized_keys;
  revoke_users -> helper logs off all of the user's WTS sessions;
  sudo_rules logged as no direct equivalent

Tray enrichment:
- Open Config (opens agent.yml), Clear enrollment (re-enroll) menu items
- set_auto_vpn persists; vpn_connect/vpn_disconnect/reinit/open_config commands
  handled by the daemon (tray_server.go)

Packaging & release:
- installer/windows/installer.iss: fully-offline Inno Setup bundle (agent,
  tray, helper, vendor-signed WireGuard MSI, OpenCredential CP, VC++ redist),
  /SILENT /SERVER_URL /JOIN_KEY parameters, SYSTEM service + HKLM Run tray
  autostart, Users-writable %ProgramData%\Theta42 for the IPC socket
- .github/workflows/build-windows.yml: build + test, pinned vendor downloads,
  ISCC compile, Azure Trusted Signing (OIDC), SHA256SUMS, GH release attach,
  optional SSO resource publish
- agent.yml.example documents auto_vpn, wireguard, service_name,
  desktop_helper, public_ip_detect

Tests:
- wireguard_apply/remove dispatch (allowed + capability-denied), PersistAutoVPN,
  ClearEnrollment; dispatch tests pin linuxPlatformOps with a temp WireGuard conf
- end-to-end verified against a local mock SSO on Windows: join-key enrollment
  (token persisted, join key blanked), discovery/telemetry pushed, signed
  arbitrary_bash verified + executed via powershell -EncodedCommand; tray IPC
  socket binds %ProgramData%\Theta42; LDAP byte-pump binds 127.0.0.1:389;
  helper update swap verified

Rebuilds all tracked dist binaries (v2.1.0).

platform_linuxops.go

@@ -15,7 +15,9 @@ import (
 )
 
 type linuxPlatformOps struct {
-	exec Executor
+	exec       Executor
+	tunnelName string // WireGuard interface/tunnel name
+	confPath   string // persisted peer config path
 }
 
 func (p *linuxPlatformOps) Reboot() ([]byte, error) {
@@ -156,3 +158,58 @@ func (p *linuxPlatformOps) ApplyUpdate(downloadURL, checksum string) error {
 func (p *linuxPlatformOps) SelfRestart() {
 	os.Exit(0)
 }
+
+// ApplyWireGuard persists the peer config and brings the tunnel up with
+// wg-quick (wg-quick reads /etc/wireguard/<name>.conf by interface name).
+func (p *linuxPlatformOps) ApplyWireGuard(conf string) error {
+	if err := os.MkdirAll(filepath.Dir(p.confPath), 0700); err != nil {
+		return fmt.Errorf("wireguard: create config dir: %w", err)
+	}
+	if err := os.WriteFile(p.confPath, []byte(conf), 0600); err != nil {
+		return fmt.Errorf("wireguard: persist config: %w", err)
+	}
+	out, err := p.exec.Execute("wg-quick", "up", p.tunnelName)
+	if err != nil {
+		return fmt.Errorf("wireguard: wg-quick up %s: %v: %s", p.tunnelName, err, out)
+	}
+	return nil
+}
+
+func (p *linuxPlatformOps) RemoveWireGuard() error {
+	out, err := p.exec.Execute("wg-quick", "down", p.tunnelName)
+	if err != nil {
+		return fmt.Errorf("wireguard: wg-quick down %s: %v: %s", p.tunnelName, err, out)
+	}
+	return nil
+}
+
+// WireGuardState reports whether the tunnel interface exists.
+func (p *linuxPlatformOps) WireGuardState() bool {
+	out, err := p.exec.Execute("ip", "link", "show", p.tunnelName)
+	return err == nil && len(out) > 0
+}
+
+// ConnectWireGuard brings the persisted config up unless already active.
+func (p *linuxPlatformOps) ConnectWireGuard() error {
+	if p.WireGuardState() {
+		return nil
+	}
+	conf, err := os.ReadFile(p.confPath)
+	if err != nil {
+		return fmt.Errorf("wireguard: no persisted config at %s: %w", p.confPath, err)
+	}
+	return p.ApplyWireGuard(string(conf))
+}
+
+func (p *linuxPlatformOps) DisconnectWireGuard() error {
+	if !p.WireGuardState() {
+		return nil
+	}
+	return p.RemoveWireGuard()
+}
+
+// ApplyIAM is the Linux node-identity engine (sudoers.d, SSH keys, PAM access,
+// SSSD cache flush + session kill).
+func (p *linuxPlatformOps) ApplyIAM(payload IAMPayload) error {
+	return applyIAM(payload, p.exec)
+}