feat(telegram,game): single bot + per-user variant preferences

Collapse the two per-language Telegram bots into one unified bot and
replace language-based variant gating with explicit per-user variant
preferences.

- Telegram: one bot; drop service_language and the supported_languages
  set everywhere (DB, account, auth, FlatBuffers Session wire, gateway,
  connector proto). The single bot renders chat and out-of-app push in
  the recipient's preferred_language; remove the game-language push
  routing override (notify Intent.Language / push Event.language).
- Preferences: new accounts.variant_preferences (text[], DB default
  {erudit_ru}, CHECK non-empty + subset of the three variants). Gates
  the New Game picker, vs-AI and the friend invitation the player
  creates, enforced server-side (HTTP 400 otherwise); an invited friend
  may still accept any variant. Edited on the Settings screen; variants
  are Erudit-first everywhere.
- Admin: drop the per-bot language selectors (broadcast / send-to-user)
  and the feedback channel_lang column/field.
- Env/CI: collapse TELEGRAM_BOT_TOKEN_{EN,RU}, TELEGRAM_GAME_CHANNEL_ID_{EN,RU},
  VITE_TELEGRAM_LINK{,_EN,_RU} and VITE_TELEGRAM_GAME_CHANNEL_NAME_{EN,RU}
  to single unsuffixed names; drop GATEWAY_DEFAULT_SUPPORTED_LANGUAGES.
- Docs updated (ARCHITECTURE, FUNCTIONAL + _ru, platform/telegram, gateway,
  backend, ui, UI_DESIGN, PRERELEASE).

The migration squash is deferred to a follow-up PR.

ui/src/gen/fbs/scrabblefb/profile.ts

@@ -95,8 +95,20 @@ banner(obj?:BannerInfo):BannerInfo|null {
   return offset ? (obj || new BannerInfo()).__init(this.bb!.__indirect(this.bb_pos + offset), this.bb!) : null;
 }
 
+variantPreferences(index: number):string
+variantPreferences(index: number,optionalEncoding:flatbuffers.Encoding):string|Uint8Array
+variantPreferences(index: number,optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 28);
+  return offset ? this.bb!.__string(this.bb!.__vector(this.bb_pos + offset) + index * 4, optionalEncoding) : null;
+}
+
+variantPreferencesLength():number {
+  const offset = this.bb!.__offset(this.bb_pos, 28);
+  return offset ? this.bb!.__vector_len(this.bb_pos + offset) : 0;
+}
+
 static startProfile(builder:flatbuffers.Builder) {
-  builder.startObject(12);
+  builder.startObject(13);
 }
 
 static addUserId(builder:flatbuffers.Builder, userIdOffset:flatbuffers.Offset) {
@@ -147,6 +159,22 @@ static addBanner(builder:flatbuffers.Builder, bannerOffset:flatbuffers.Offset) {
   builder.addFieldOffset(11, bannerOffset, 0);
 }
 
+static addVariantPreferences(builder:flatbuffers.Builder, variantPreferencesOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(12, variantPreferencesOffset, 0);
+}
+
+static createVariantPreferencesVector(builder:flatbuffers.Builder, data:flatbuffers.Offset[]):flatbuffers.Offset {
+  builder.startVector(4, data.length, 4);
+  for (let i = data.length - 1; i >= 0; i--) {
+    builder.addOffset(data[i]!);
+  }
+  return builder.endVector();
+}
+
+static startVariantPreferencesVector(builder:flatbuffers.Builder, numElems:number) {
+  builder.startVector(4, numElems, 4);
+}
+
 static endProfile(builder:flatbuffers.Builder):flatbuffers.Offset {
   const offset = builder.endObject();
   return offset;

ui/src/gen/fbs/scrabblefb/session.ts

@@ -46,27 +46,8 @@ displayName(optionalEncoding?:any):string|Uint8Array|null {
   return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
 }
 
-supportedLanguages(index: number):string
-supportedLanguages(index: number,optionalEncoding:flatbuffers.Encoding):string|Uint8Array
-supportedLanguages(index: number,optionalEncoding?:any):string|Uint8Array|null {
-  const offset = this.bb!.__offset(this.bb_pos, 12);
-  return offset ? this.bb!.__string(this.bb!.__vector(this.bb_pos + offset) + index * 4, optionalEncoding) : null;
-}
-
-supportedLanguagesLength():number {
-  const offset = this.bb!.__offset(this.bb_pos, 12);
-  return offset ? this.bb!.__vector_len(this.bb_pos + offset) : 0;
-}
-
-serviceLanguage():string|null
-serviceLanguage(optionalEncoding:flatbuffers.Encoding):string|Uint8Array|null
-serviceLanguage(optionalEncoding?:any):string|Uint8Array|null {
-  const offset = this.bb!.__offset(this.bb_pos, 14);
-  return offset ? this.bb!.__string(this.bb_pos + offset, optionalEncoding) : null;
-}
-
 static startSession(builder:flatbuffers.Builder) {
-  builder.startObject(6);
+  builder.startObject(4);
 }
 
 static addToken(builder:flatbuffers.Builder, tokenOffset:flatbuffers.Offset) {
@@ -85,39 +66,17 @@ static addDisplayName(builder:flatbuffers.Builder, displayNameOffset:flatbuffers
   builder.addFieldOffset(3, displayNameOffset, 0);
 }
 
-static addSupportedLanguages(builder:flatbuffers.Builder, supportedLanguagesOffset:flatbuffers.Offset) {
-  builder.addFieldOffset(4, supportedLanguagesOffset, 0);
-}
-
-static createSupportedLanguagesVector(builder:flatbuffers.Builder, data:flatbuffers.Offset[]):flatbuffers.Offset {
-  builder.startVector(4, data.length, 4);
-  for (let i = data.length - 1; i >= 0; i--) {
-    builder.addOffset(data[i]!);
-  }
-  return builder.endVector();
-}
-
-static startSupportedLanguagesVector(builder:flatbuffers.Builder, numElems:number) {
-  builder.startVector(4, numElems, 4);
-}
-
-static addServiceLanguage(builder:flatbuffers.Builder, serviceLanguageOffset:flatbuffers.Offset) {
-  builder.addFieldOffset(5, serviceLanguageOffset, 0);
-}
-
 static endSession(builder:flatbuffers.Builder):flatbuffers.Offset {
   const offset = builder.endObject();
   return offset;
 }
 
-static createSession(builder:flatbuffers.Builder, tokenOffset:flatbuffers.Offset, userIdOffset:flatbuffers.Offset, isGuest:boolean, displayNameOffset:flatbuffers.Offset, supportedLanguagesOffset:flatbuffers.Offset, serviceLanguageOffset:flatbuffers.Offset):flatbuffers.Offset {
+static createSession(builder:flatbuffers.Builder, tokenOffset:flatbuffers.Offset, userIdOffset:flatbuffers.Offset, isGuest:boolean, displayNameOffset:flatbuffers.Offset):flatbuffers.Offset {
   Session.startSession(builder);
   Session.addToken(builder, tokenOffset);
   Session.addUserId(builder, userIdOffset);
   Session.addIsGuest(builder, isGuest);
   Session.addDisplayName(builder, displayNameOffset);
-  Session.addSupportedLanguages(builder, supportedLanguagesOffset);
-  Session.addServiceLanguage(builder, serviceLanguageOffset);
   return Session.endSession(builder);
 }
 }

ui/src/gen/fbs/scrabblefb/update-profile-request.ts

@@ -70,8 +70,20 @@ notificationsInAppOnly():boolean {
   return offset ? !!this.bb!.readInt8(this.bb_pos + offset) : true;
 }
 
+variantPreferences(index: number):string
+variantPreferences(index: number,optionalEncoding:flatbuffers.Encoding):string|Uint8Array
+variantPreferences(index: number,optionalEncoding?:any):string|Uint8Array|null {
+  const offset = this.bb!.__offset(this.bb_pos, 20);
+  return offset ? this.bb!.__string(this.bb!.__vector(this.bb_pos + offset) + index * 4, optionalEncoding) : null;
+}
+
+variantPreferencesLength():number {
+  const offset = this.bb!.__offset(this.bb_pos, 20);
+  return offset ? this.bb!.__vector_len(this.bb_pos + offset) : 0;
+}
+
 static startUpdateProfileRequest(builder:flatbuffers.Builder) {
-  builder.startObject(8);
+  builder.startObject(9);
 }
 
 static addDisplayName(builder:flatbuffers.Builder, displayNameOffset:flatbuffers.Offset) {
@@ -106,12 +118,28 @@ static addNotificationsInAppOnly(builder:flatbuffers.Builder, notificationsInApp
   builder.addFieldInt8(7, +notificationsInAppOnly, +true);
 }
 
+static addVariantPreferences(builder:flatbuffers.Builder, variantPreferencesOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(8, variantPreferencesOffset, 0);
+}
+
+static createVariantPreferencesVector(builder:flatbuffers.Builder, data:flatbuffers.Offset[]):flatbuffers.Offset {
+  builder.startVector(4, data.length, 4);
+  for (let i = data.length - 1; i >= 0; i--) {
+    builder.addOffset(data[i]!);
+  }
+  return builder.endVector();
+}
+
+static startVariantPreferencesVector(builder:flatbuffers.Builder, numElems:number) {
+  builder.startVector(4, numElems, 4);
+}
+
 static endUpdateProfileRequest(builder:flatbuffers.Builder):flatbuffers.Offset {
   const offset = builder.endObject();
   return offset;
 }
 
-static createUpdateProfileRequest(builder:flatbuffers.Builder, displayNameOffset:flatbuffers.Offset, preferredLanguageOffset:flatbuffers.Offset, timeZoneOffset:flatbuffers.Offset, awayStartOffset:flatbuffers.Offset, awayEndOffset:flatbuffers.Offset, blockChat:boolean, blockFriendRequests:boolean, notificationsInAppOnly:boolean):flatbuffers.Offset {
+static createUpdateProfileRequest(builder:flatbuffers.Builder, displayNameOffset:flatbuffers.Offset, preferredLanguageOffset:flatbuffers.Offset, timeZoneOffset:flatbuffers.Offset, awayStartOffset:flatbuffers.Offset, awayEndOffset:flatbuffers.Offset, blockChat:boolean, blockFriendRequests:boolean, notificationsInAppOnly:boolean, variantPreferencesOffset:flatbuffers.Offset):flatbuffers.Offset {
   UpdateProfileRequest.startUpdateProfileRequest(builder);
   UpdateProfileRequest.addDisplayName(builder, displayNameOffset);
   UpdateProfileRequest.addPreferredLanguage(builder, preferredLanguageOffset);
@@ -121,6 +149,7 @@ static createUpdateProfileRequest(builder:flatbuffers.Builder, displayNameOffset
   UpdateProfileRequest.addBlockChat(builder, blockChat);
   UpdateProfileRequest.addBlockFriendRequests(builder, blockFriendRequests);
   UpdateProfileRequest.addNotificationsInAppOnly(builder, notificationsInAppOnly);
+  UpdateProfileRequest.addVariantPreferences(builder, variantPreferencesOffset);
   return UpdateProfileRequest.endUpdateProfileRequest(builder);
 }
 }