Merge main into ui-refactor; port MDM support to the Wails UI

Integrates main's MDM configuration-profile feature and adapts it to the
Wails UI (this branch had already replaced the Fyne UI).

Conflict resolution:
- go.mod/go.sum: take main's deps; howett.net/plist pinned to v1.0.2-... (tidy)
- client/proto/daemon.pb.go: regenerated from the merged daemon.proto
- client/internal/peer/status.go: union of ipToKey (main) + sessionExpiresAt (HEAD)
- client/server/server.go: main's intent/liveness model (connectionGoroutineRunning,
  clientRunning no longer cleared by the goroutine) + empty-PSK guard
- client/ui/client_ui.go, client/ui/profile.go: removed (dead Fyne UI)

MDM port (backend + tray):
- services/settings.go: expose MDMManagedFields plus a managedFields map keyed
  by Config field names so the settings form can gate a control without
  translating mdm.Key* names
- tray: gate Profiles / Exit Node menus on DisableProfiles / DisableNetworks via
  GetFeatures, refreshed on the config_changed system event (replaces the legacy
  2s poll); localized MDM policy-applied toast in all shipped locales
- client/proto/metadata.go: shared constants for the config_changed /
  policy_applied event markers

PreSharedKey: GetConfig now returns preSharedKeySet (bool) instead of the masked
value; the settings form provides its own placeholder and sends a new key only
when the user types one.

client/internal/debug/debug.go

@@ -530,6 +530,14 @@ func (g *BundleGenerator) addConfig() error {
 		}
 	}
 
+	// Surface the set of MDM-enforced keys so a support engineer reading
+	// the bundle can tell which field values are user-set vs MDM-overridden.
+	// Same semantics as the mDMManagedFields list returned by the
+	// GetConfig RPC consumed by `netbird debug config`.
+	if managed := g.internalConfig.Policy().ManagedKeys(); len(managed) > 0 {
+		configContent.WriteString(fmt.Sprintf("MDMManagedFields: %v\n", managed))
+	}
+
 	configReader := strings.NewReader(configContent.String())
 	if err := g.addFileToZip(configReader, "config.txt"); err != nil {
 		return fmt.Errorf("add config file to zip: %w", err)