Merge branch 'main' into fix/pkce-flow-session-extend

Both sides extended the OAuth flow entry points: main threads a login hint
through GetOAuthFlow/NewOAuthFlow, this branch threads a sessionExtend flag.
The merged signatures carry both.

client/android/login.go keeps main's structure — the hint reaches the flow
through GetOAuthFlow rather than a loginHintSetter assertion, profile email
helpers live in client/mobile, and runOAuthFlow is the shared driver — with
this branch's sessionExtend plumbing and wrong-account retry layered on top.
The branch's runInteractiveFlow is dropped in favour of runOAuthFlow.

client/android/ssh_client.go is new from main and merged without conflict,
but calls NewOAuthFlow; SSH login is a fresh login, so it passes false.

management.pb.go regenerated with the pinned protoc-gen-go v1.26 from
generate.sh. The .proto merged cleanly: main's LazyState and proxy_embedded
are disjoint from this branch's SessionExtend field.

shared/management/client/client_test.go

@@ -8,7 +8,7 @@ import (
 	"testing"
 	"time"
 
-	"github.com/golang/mock/gomock"
+	"go.uber.org/mock/gomock"
 	log "github.com/sirupsen/logrus"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -591,7 +591,7 @@ func Test_GetPKCEAuthorizationFlow(t *testing.T) {
 	expectedFlowInfo := &mgmtProto.PKCEAuthorizationFlow{
 		ProviderConfig: &mgmtProto.ProviderConfig{
 			ClientID:     "client",
-			ClientSecret: "secret",
+			ClientSecret: "secret", //nolint:staticcheck
 		},
 	}