feat(profile): carry linked identities in the profile (email, telegram, vk)

Add email / telegram_linked / vk_linked to the Profile (fbs table + regenerated
Go/TS bindings, gateway ProfileResp + encodeProfile, backend DTO, UI model +
decode). They are filled outside the pure projection — Server.profileResponse now
reads the account's identities (like the banner seam) — and will drive the profile's
Add / Unlink / change-email controls.

gateway/internal/backendclient/api.go

@@ -37,6 +37,11 @@ type ProfileResp struct {
 	// Banner is the advertising-banner block, present only for a viewer eligible to
 	// see the banner. The gateway forwards it verbatim into the Profile payload.
 	Banner *BannerResp `json:"banner,omitempty"`
+	// Email is the confirmed email ("" when none); TelegramLinked/VkLinked report an
+	// attached platform identity — they drive the profile's link/unlink/change controls.
+	Email          string `json:"email"`
+	TelegramLinked bool   `json:"telegram_linked"`
+	VkLinked       bool   `json:"vk_linked"`
 }
 
 // BannerResp is the advertising-banner block of an eligible viewer's profile: the

gateway/internal/transcode/encode.go

@@ -76,6 +76,7 @@ func encodeProfile(p backendclient.ProfileResp) []byte {
 	tz := b.CreateString(p.TimeZone)
 	awayStart := b.CreateString(p.AwayStart)
 	awayEnd := b.CreateString(p.AwayEnd)
+	email := b.CreateString(p.Email)
 	// Build the banner table (and its children) before opening Profile: FlatBuffers
 	// forbids a nested table while another is under construction.
 	var banner flatbuffers.UOffsetT
@@ -96,6 +97,9 @@ func encodeProfile(p backendclient.ProfileResp) []byte {
 	fb.ProfileAddAwayEnd(b, awayEnd)
 	fb.ProfileAddNotificationsInAppOnly(b, p.NotificationsInAppOnly)
 	fb.ProfileAddVariantPreferences(b, prefs)
+	fb.ProfileAddEmail(b, email)
+	fb.ProfileAddTelegramLinked(b, p.TelegramLinked)
+	fb.ProfileAddVkLinked(b, p.VkLinked)
 	if p.Banner != nil {
 		fb.ProfileAddBanner(b, banner)
 	}