Remove sponsor token gating

Unlock all locally gated features without a sponsor token. The change sits
in util/sponsor/auth.go instead of the ~68 device constructors:

- Subject defaults to a non-empty value, so RedactedStatus reports an active
  sponsorship and the frontend unlocks isSponsor
- IsAuthorized always returns true, opening every caller including the
  modbus proxy and the optimizer gate
- ConfigureSponsorship still validates a configured token but never fails,
  so an expired token no longer aborts startup

Drops TestAlpitronicSponsorGate and TestSigenergyEVDCSponsorGate, which
asserted exactly the gate that is removed here.

Cloud-backed services (optimizer API, remote access, cloud vehicles,
telemetry) still require a real token - those are checked server side.

See FORK.md.

FORK.md

@@ -0,0 +1,54 @@
+# Fork-Hinweise
+
+Fork von [evcc-io/evcc](https://github.com/evcc-io/evcc).
+
+## Abweichung vom Upstream
+
+Das Sponsor-Gating ist entfernt: alle lokal geprüften Features stehen ohne
+Sponsor-Token zur Verfügung. Der Eingriff sitzt an einer einzigen Stelle in
+`util/sponsor/auth.go`, statt in den ~68 Geräte-Konstruktoren:
+
+- `Subject` ist per Default nicht leer (`"unlocked"`). Damit meldet
+  `RedactedStatus()` einen aktiven Sponsor-Status, und das Frontend schaltet
+  `isSponsor` (`assets/js/views/Config.vue`) frei — Geräte-Dialoge zeigen kein
+  „Sponsor-Token erforderlich" mehr.
+- `IsAuthorized()` liefert immer `true`. Das öffnet alle Aufrufer, u. a. die
+  Charger-/Vehicle-Konstruktoren, `server/modbus/proxy.go` und den
+  Optimizer-Gate in `core/site_optimizer.go`.
+- `ConfigureSponsorship()` validiert ein hinterlegtes Token weiterhin, gibt aber
+  nie einen Fehler zurück. Ein abgelaufenes oder ungültiges Token bricht den
+  Start damit nicht mehr ab; es wird nur verworfen, damit es keinen
+  Cloud-Diensten angeboten wird.
+
+Zusätzlich entfernt: `TestAlpitronicSponsorGate` und
+`TestSigenergyEVDCSponsorGate` — beide prüften genau das Gate, das hier
+absichtlich nicht mehr existiert.
+
+## Was das *nicht* freischaltet
+
+Serverseitig geprüfte Dienste brauchen weiterhin ein echtes Token, weil die
+Prüfung bei evcc.io stattfindet und nicht im Client:
+
+- Optimizer-API (`core/site_optimizer.go` sendet `Bearer <token>`)
+- Remote Access / Tunnel (`server/remote/`)
+- Cloud-Fahrzeuge und Tronity (`vehicle/cloud.go`, `vehicle/tronity.go`)
+- Telemetrie (`util/telemetry/`, hängt an `IsAuthorizedForApi()`)
+
+## Lizenz
+
+Der Hauptteil von evcc steht unter MIT. `util/sponsor/` trägt einen eigenen
+Vermerk („This module is NOT covered by the MIT license. All rights reserved.").
+Diese Änderung betrifft genau dieses Modul.
+
+evcc finanziert sich über Sponsoring: <https://sponsor.evcc.io>
+
+## Upstream-Sync
+
+```
+git remote add upstream https://github.com/evcc-io/evcc.git
+git fetch upstream
+git rebase upstream/master
+```
+
+Konflikte sind auf `util/sponsor/auth.go` beschränkt; `FORK.md` liegt bewusst
+außerhalb der Upstream-Dateien.

charger/alpitronic_test.go

@@ -10,7 +10,6 @@ import (
 	"github.com/andig/mbserver"
 	"github.com/evcc-io/evcc/api"
 	"github.com/evcc-io/evcc/util/modbus"
-	"github.com/evcc-io/evcc/util/sponsor"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -362,14 +361,3 @@ func TestAlpitronicReadFailure(t *testing.T) {
 	_, err = wb.CurrentPower()
 	assert.Error(t, err)
 }
-
-func TestAlpitronicSponsorGate(t *testing.T) {
-	// go-e tests set the global sponsor.Subject and never reset it
-	old := sponsor.Subject
-	sponsor.Subject = ""
-	t.Cleanup(func() { sponsor.Subject = old })
-
-	// tests run without sponsorship: the public constructor must refuse
-	_, err := NewAlpitronicHYC(t.Context(), modbus.TcpSettings{URI: "localhost:0", ID: 1}, 1)
-	assert.ErrorIs(t, err, api.ErrSponsorRequired)
-}

charger/sigenergy-evdc_test.go

@@ -10,7 +10,6 @@ import (
 	"github.com/andig/mbserver"
 	"github.com/evcc-io/evcc/api"
 	"github.com/evcc-io/evcc/util/modbus"
-	"github.com/evcc-io/evcc/util/sponsor"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -290,17 +289,6 @@ func TestSigenergyEVDCMinMaxCurrent(t *testing.T) {
 	assert.InDelta(t, 36.23, maxA, 0.01) // 25000 W / 690
 }
 
-func TestSigenergyEVDCSponsorGate(t *testing.T) {
-	// go-e tests set the global sponsor.Subject and never reset it
-	old := sponsor.Subject
-	sponsor.Subject = ""
-	t.Cleanup(func() { sponsor.Subject = old })
-
-	// tests run without sponsorship: the public constructor must refuse
-	_, err := NewSigenergyEVDC(t.Context(), "localhost:0", 1)
-	assert.ErrorIs(t, err, api.ErrSponsorRequired)
-}
-
 func TestSigenergyEVDCReadFailure(t *testing.T) {
 	// missing register in the bulk-read block -> IllegalDataAddress propagates
 	regs := evdcRegs(evdcStateCharging)

util/sponsor/auth.go

@@ -35,9 +35,14 @@ import (
 	"google.golang.org/grpc/status"
 )
 
+// unlocked is the sponsorship subject used by this fork. Sponsor gating is
+// removed here, so Subject is never empty and IsAuthorized always holds.
+const unlocked = "unlocked"
+
 var (
 	mu        sync.RWMutex
-	Subject, Token string
+	Subject   = unlocked
+	Token     string
 	ExpiresAt time.Time
 )
 
@@ -51,9 +56,8 @@ const unavailable = "sponsorship unavailable"
 const startupTimeout = 30 * time.Second
 
 func IsAuthorized() bool {
-	mu.RLock()
+	// sponsorship gating removed in this fork
-	defer mu.RUnlock()
+	return true
-	return len(Subject) > 0
 }
 
 func IsAuthorizedForApi() bool {
@@ -62,8 +66,29 @@ func IsAuthorizedForApi() bool {
 	return IsAuthorized() && Subject != unavailable && Token != ""
 }
 
-// check and set sponsorship token
+// ConfigureSponsorship validates a sponsor token when one is configured, but
+// never fails: sponsorship is not required in this fork. A valid token is
+// still picked up so cloud-backed services keep working for real sponsors.
 func ConfigureSponsorship(token string) error {
+	err := configureSponsorship(token)
+
+	mu.Lock()
+	defer mu.Unlock()
+
+	if err != nil {
+		// stay unlocked, but do not offer a rejected token to cloud services
+		Token = ""
+	}
+
+	if Subject == "" {
+		Subject = unlocked
+	}
+
+	return nil
+}
+
+// check and set sponsorship token
+func configureSponsorship(token string) error {
 	mu.Lock()
 	defer mu.Unlock()