R6(a): de-stage code, docs, READMEs; split stage6_test

Mechanical, behaviour-preserving removal of Stage N / TODO-N / phase (RN)
references from comments, doc-comments, service READMEs, the current-state docs
(ARCHITECTURE, FUNCTIONAL+_ru, TESTING, UI_DESIGN), config-file comments, and the
.fbs/.proto schema comments. PLAN.md / PRERELEASE.md / CLAUDE.md keep the stage
history.

- Rename the only stage-named identifiers: registerStage8 -> registerSocialOps,
  registerStage11 -> registerLinkOps (gateway transcode).
- Split stage6_test.go: TestEmailLoginFlow -> email_test.go,
  TestGuestAutoMatchLeavesNoStats (+ provisionGuest) -> account_test.go.
- Regenerated proto bindings (push.pb.go, telegram_grpc.pb.go) from the de-staged
  .proto comments; FB Go/TS bindings unchanged (flatc strips schema comments).

go build/vet/gofmt clean across modules; integration typecheck and pnpm check green.

pkg/proto/push/v1/push.pb.go

@@ -84,7 +84,7 @@ type Event struct {
 	Kind    string                 `protobuf:"bytes,2,opt,name=kind,proto3" json:"kind,omitempty"`
 	Payload []byte                 `protobuf:"bytes,3,opt,name=payload,proto3" json:"payload,omitempty"`
 	EventId string                 `protobuf:"bytes,4,opt,name=event_id,json=eventId,proto3" json:"event_id,omitempty"`
-	// language routes an out-of-app push to a specific per-language bot (Stage 17): for a game
+	// language routes an out-of-app push to a specific per-language bot: for a game
 	// event it carries the game's language ("en"/"ru") so the notification comes from the game's
 	// bot rather than the recipient's last-login bot. Empty falls back to the recipient's service
 	// language at the gateway.

pkg/proto/push/v1/push.proto

@@ -33,7 +33,7 @@ message Event {
   string kind = 2;
   bytes payload = 3;
   string event_id = 4;
-  // language routes an out-of-app push to a specific per-language bot (Stage 17): for a game
+  // language routes an out-of-app push to a specific per-language bot: for a game
   // event it carries the game's language ("en"/"ru") so the notification comes from the game's
   // bot rather than the recipient's last-login bot. Empty falls back to the recipient's service
   // language at the gateway.

pkg/proto/telegram/v1/telegram.proto

@@ -23,7 +23,7 @@ service Telegram {
   // ValidateLoginWidget verifies Telegram Login Widget authorization data (the web
   // sign-in flow, HMAC under SHA-256(bot_token)) and returns the authenticated
   // user. The gateway calls it during the link.telegram edge operation to attach a
-  // Telegram identity to an existing account (Stage 11).
+  // Telegram identity to an existing account.
   rpc ValidateLoginWidget(ValidateLoginWidgetRequest) returns (ValidateLoginWidgetResponse);
   // Notify delivers an out-of-app notification for a backend push event. The
   // gateway calls it only for a recipient with no live in-app stream (so the
@@ -32,11 +32,11 @@ service Telegram {
   // payload; unrenderable kinds are skipped (delivered=false).
   rpc Notify(NotifyRequest) returns (NotifyResponse);
   // SendToUser sends an arbitrary text message to one user through the bot the
-  // request selects by language (admin use, wired in Stage 10). delivered is false
+  // request selects by language (admin use). delivered is false
   // when the user has not started that bot.
   rpc SendToUser(SendToUserRequest) returns (SendResponse);
   // SendToGameChannel posts an arbitrary text message to the game channel of the
-  // bot the request selects by language (admin use, wired in Stage 10); the channel
+  // bot the request selects by language (admin use); the channel
   // ids live only in the connector configuration.
   rpc SendToGameChannel(SendToGameChannelRequest) returns (SendResponse);
 }

pkg/proto/telegram/v1/telegram_grpc.pb.go

@@ -50,7 +50,7 @@ type TelegramClient interface {
 	// ValidateLoginWidget verifies Telegram Login Widget authorization data (the web
 	// sign-in flow, HMAC under SHA-256(bot_token)) and returns the authenticated
 	// user. The gateway calls it during the link.telegram edge operation to attach a
-	// Telegram identity to an existing account (Stage 11).
+	// Telegram identity to an existing account.
 	ValidateLoginWidget(ctx context.Context, in *ValidateLoginWidgetRequest, opts ...grpc.CallOption) (*ValidateLoginWidgetResponse, error)
 	// Notify delivers an out-of-app notification for a backend push event. The
 	// gateway calls it only for a recipient with no live in-app stream (so the
@@ -59,11 +59,11 @@ type TelegramClient interface {
 	// payload; unrenderable kinds are skipped (delivered=false).
 	Notify(ctx context.Context, in *NotifyRequest, opts ...grpc.CallOption) (*NotifyResponse, error)
 	// SendToUser sends an arbitrary text message to one user through the bot the
-	// request selects by language (admin use, wired in Stage 10). delivered is false
+	// request selects by language (admin use). delivered is false
 	// when the user has not started that bot.
 	SendToUser(ctx context.Context, in *SendToUserRequest, opts ...grpc.CallOption) (*SendResponse, error)
 	// SendToGameChannel posts an arbitrary text message to the game channel of the
-	// bot the request selects by language (admin use, wired in Stage 10); the channel
+	// bot the request selects by language (admin use); the channel
 	// ids live only in the connector configuration.
 	SendToGameChannel(ctx context.Context, in *SendToGameChannelRequest, opts ...grpc.CallOption) (*SendResponse, error)
 }
@@ -139,7 +139,7 @@ type TelegramServer interface {
 	// ValidateLoginWidget verifies Telegram Login Widget authorization data (the web
 	// sign-in flow, HMAC under SHA-256(bot_token)) and returns the authenticated
 	// user. The gateway calls it during the link.telegram edge operation to attach a
-	// Telegram identity to an existing account (Stage 11).
+	// Telegram identity to an existing account.
 	ValidateLoginWidget(context.Context, *ValidateLoginWidgetRequest) (*ValidateLoginWidgetResponse, error)
 	// Notify delivers an out-of-app notification for a backend push event. The
 	// gateway calls it only for a recipient with no live in-app stream (so the
@@ -148,11 +148,11 @@ type TelegramServer interface {
 	// payload; unrenderable kinds are skipped (delivered=false).
 	Notify(context.Context, *NotifyRequest) (*NotifyResponse, error)
 	// SendToUser sends an arbitrary text message to one user through the bot the
-	// request selects by language (admin use, wired in Stage 10). delivered is false
+	// request selects by language (admin use). delivered is false
 	// when the user has not started that bot.
 	SendToUser(context.Context, *SendToUserRequest) (*SendResponse, error)
 	// SendToGameChannel posts an arbitrary text message to the game channel of the
-	// bot the request selects by language (admin use, wired in Stage 10); the channel
+	// bot the request selects by language (admin use); the channel
 	// ids live only in the connector configuration.
 	SendToGameChannel(context.Context, *SendToGameChannelRequest) (*SendResponse, error)
 	mustEmbedUnimplementedTelegramServer()