admin: gift granting, collectible attribute/number control, and Layer 228 moderation tools

Admin console additions (Layer 228):
- Give Gifts: dedicated tab with sorted Lottie/TGS gift picker + inline form; grant any catalog gift to a user/channel from 777000 (no charge)
- Upgraded/collectible delivery: mint a unique gift with admin-selected model/pattern/backdrop and custom number, or random/auto (DB FK + UNIQUE(gift_id,num) enforce invariants)
- SCAM/FAKE flags for users/channels (migration 0136) with configurable profile warning (TELESRV_SCAM_WARNING/TELESRV_FAKE_WARNING)
- Support toggle, force channel settings incl. gigagroup (migration 0137), username management, cosmetic color/emoji-status
- Emoji admin tab (custom emoji list + document IDs + Lottie/TGS preview)
- Bot management; soft UI / dark theme
Wired through Router -> admin.Service -> adminapi -> BFF -> React panel (en/zh/ru).

internal/domain/channel.go

@@ -415,6 +415,9 @@ type Channel struct {
 	About                    string
 	Username                 string
 	Verified                 bool
+	Scam                     bool
+	Fake                     bool
+	Gigagroup                bool
 	Broadcast                bool
 	Megagroup                bool
 	Forum                    bool
@@ -1443,6 +1446,25 @@ type UpdateChannelUsernameRequest struct {
 	Username  string
 }
 
+// ChannelAdminSettings is an admin-direct patch of channel moderation settings.
+// nil fields are left unchanged; set fields are applied verbatim (no membership
+// or permission checks — this is the operator/admin path).
+type ChannelAdminSettings struct {
+	Gigagroup          *bool
+	AntiSpam           *bool
+	ParticipantsHidden *bool
+	NoForwards         *bool
+	JoinToSend         *bool
+	JoinRequest        *bool
+	SlowmodeSeconds    *int
+}
+
+// Empty reports whether the patch changes nothing.
+func (p ChannelAdminSettings) Empty() bool {
+	return p.Gigagroup == nil && p.AntiSpam == nil && p.ParticipantsHidden == nil &&
+		p.NoForwards == nil && p.JoinToSend == nil && p.JoinRequest == nil && p.SlowmodeSeconds == nil
+}
+
 // SetChannelPhotoResult describes a channel avatar mutation and its durable
 // service message.
 type SetChannelPhotoResult struct {