admin: add account spam restriction (join/message gate)

Adds a narrower spam sanction alongside the existing account freeze: a
restricted account keeps every existing membership and conversation, but
cannot join new channels/groups (public join or invite link) and cannot
start a new conversation with a non-contact. Reachable both as a standalone
admin action and as a decision on a reported user's moderation case, with
the same idempotent-supersession and appeal wiring freeze already has.

internal/app/users/service.go

@@ -28,13 +28,14 @@ type ProfilePhotoProvider = userprojection.ProfilePhotoProvider
 
 // Service 提供用户查询。
 type Service struct {
-	users     store.UserStore
-	cache     store.UserCache
-	contacts  store.ContactStore
-	photos    ProfilePhotoProvider
-	privacy   userprojection.PrivacyEvaluator
-	freezes   userprojection.AccountFreezeProvider
-	projector *userprojection.Projector
+	users        store.UserStore
+	cache        store.UserCache
+	contacts     store.ContactStore
+	photos       ProfilePhotoProvider
+	privacy      userprojection.PrivacyEvaluator
+	freezes      userprojection.AccountFreezeProvider
+	restrictions userprojection.AccountRestrictionProvider
+	projector    *userprojection.Projector
 	// hideThirdPartyVerification mirrors config.HideThirdPartyVerification:
 	// while true, ResolveUsername never resolves @marksbot
 	// (domain.VerifierBotUserID), so a client cannot discover it by username.
@@ -97,6 +98,11 @@ func WithAccountFreezeProvider(p userprojection.AccountFreezeProvider) Option {
 	return func(s *Service) { s.freezes = p }
 }
 
+// WithAccountRestrictionProvider injects the account spam-restriction reader.
+func WithAccountRestrictionProvider(p userprojection.AccountRestrictionProvider) Option {
+	return func(s *Service) { s.restrictions = p }
+}
+
 // WithHideThirdPartyVerification mirrors config.HideThirdPartyVerification:
 // while true, ResolveUsername treats @marksbot as not found.
 func WithHideThirdPartyVerification(hidden bool) Option {
@@ -135,6 +141,7 @@ func NewService(users store.UserStore, opts ...Option) *Service {
 		userprojection.WithPhotoProvider(s.photos),
 		userprojection.WithPrivacyEvaluator(s.privacy),
 		userprojection.WithAccountFreezeProvider(s.freezes),
+		userprojection.WithAccountRestrictionProvider(s.restrictions),
 	)
 	return s
 }