[client] Drop the non-functional admin URL (#8267)

* [client] Drop the non-functional admin URL

#4218 deprecated --admin-url, but #3980 merged right after it and restored the flag and its wiring. The value has been stored and echoed back ever since, without anything reading it.

Stop sending it from the CLI, ignore it in the daemon and drop it from the profile config, the UI settings service and the debug bundle. The proto fields stay for older clients, and the mobile getters and setters keep their signatures as deprecated stubs.

* [client] Drop adminUrl from the Wails API reference

client/ui/services/settings.go

@@ -51,7 +51,6 @@ type ConfigParams struct {
 
 type Config struct {
 	ManagementURL                 string `json:"managementUrl"`
-	AdminURL                      string `json:"adminUrl"`
 	ConfigFile                    string `json:"configFile"`
 	LogFile                       string `json:"logFile"`
 	PreSharedKeySet               bool   `json:"preSharedKeySet"`
@@ -84,7 +83,6 @@ type SetConfigParams struct {
 	ProfileName                   string  `json:"profileName"`
 	Username                      string  `json:"username"`
 	ManagementURL                 string  `json:"managementUrl"`
-	AdminURL                      string  `json:"adminUrl"`
 	InterfaceName                 *string `json:"interfaceName,omitempty"`
 	WireguardPort                 *int64  `json:"wireguardPort,omitempty"`
 	MTU                           *int64  `json:"mtu,omitempty"`
@@ -144,7 +142,6 @@ func (s *Settings) GetConfig(ctx context.Context, p ConfigParams) (Config, error
 	}
 	return Config{
 		ManagementURL:                 resp.GetManagementUrl(),
-		AdminURL:                      resp.GetAdminURL(),
 		ConfigFile:                    resp.GetConfigFile(),
 		LogFile:                       resp.GetLogFile(),
 		PreSharedKeySet:               resp.GetPreSharedKey() != "",
@@ -181,7 +178,6 @@ func (s *Settings) SetConfig(ctx context.Context, p SetConfigParams) (SaveOutcom
 		ProfileName:                   p.ProfileName,
 		Username:                      p.Username,
 		ManagementUrl:                 p.ManagementURL,
-		AdminURL:                      p.AdminURL,
 		InterfaceName:                 p.InterfaceName,
 		WireguardPort:                 p.WireguardPort,
 		Mtu:                           p.MTU,