feat(ads): server-driven ad-banner backend, wire & admin console (PR1)

Turn the gated-off mock banner into a real advertising subsystem (backend +
admin half; the UI rotation lands in PR2).

- internal/ads: campaigns (percent weight + validity window; a perpetual,
  undeletable default that fills the remainder up to 100%), 1..N bilingual
  messages (en+ru), global display timings; ActiveSet computes the
  window-filtered, default-remainder, GCD-reduced, language-resolved rotation
  feed. Smooth-weighted-round-robin math is unit-tested.
- migration 00006 (+ jetgen): ad_campaigns / ad_messages / ad_settings, seeded
  default campaign + house message + default timings.
- eligibility = !paid_account && hint_balance==0 && !no_banner role (new role;
  guests qualify). The resolved feed rides the profile.get response (no new RPC,
  works for guests, nothing distinct to filter); language by service_language.
- live update: a notify `banner` sub-kind (re-poll signal) published when an
  operator grants hints or grants/revokes no_banner, so the client shows/hides
  in place.
- admin console /_gm/banners (+ /_gm/banner-settings): campaign + message CRUD
  with reorder, default protection, clamped timings.
- wire: fbs BannerInfo/BannerCampaign on Profile; gateway transcode forwards it.
- docs: ARCHITECTURE §10, FUNCTIONAL (+ _ru), backend README, PRERELEASE tracker
  (incl. the deferred app.load aggregator note).

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

@@ -2,6 +2,9 @@
 
 import * as flatbuffers from 'flatbuffers';
 
+import { BannerInfo } from '../scrabblefb/banner-info.js';
+
+
 export class Profile {
   bb: flatbuffers.ByteBuffer|null = null;
   bb_pos = 0;
@@ -87,8 +90,13 @@ notificationsInAppOnly():boolean {
   return offset ? !!this.bb!.readInt8(this.bb_pos + offset) : true;
 }
 
+banner(obj?:BannerInfo):BannerInfo|null {
+  const offset = this.bb!.__offset(this.bb_pos, 26);
+  return offset ? (obj || new BannerInfo()).__init(this.bb!.__indirect(this.bb_pos + offset), this.bb!) : null;
+}
+
 static startProfile(builder:flatbuffers.Builder) {
-  builder.startObject(11);
+  builder.startObject(12);
 }
 
 static addUserId(builder:flatbuffers.Builder, userIdOffset:flatbuffers.Offset) {
@@ -135,24 +143,13 @@ static addNotificationsInAppOnly(builder:flatbuffers.Builder, notificationsInApp
   builder.addFieldInt8(10, +notificationsInAppOnly, +true);
 }
 
+static addBanner(builder:flatbuffers.Builder, bannerOffset:flatbuffers.Offset) {
+  builder.addFieldOffset(11, bannerOffset, 0);
+}
+
 static endProfile(builder:flatbuffers.Builder):flatbuffers.Offset {
   const offset = builder.endObject();
   return offset;
 }
 
-static createProfile(builder:flatbuffers.Builder, userIdOffset:flatbuffers.Offset, displayNameOffset:flatbuffers.Offset, preferredLanguageOffset:flatbuffers.Offset, timeZoneOffset:flatbuffers.Offset, hintBalance:number, blockChat:boolean, blockFriendRequests:boolean, isGuest:boolean, awayStartOffset:flatbuffers.Offset, awayEndOffset:flatbuffers.Offset, notificationsInAppOnly:boolean):flatbuffers.Offset {
-  Profile.startProfile(builder);
-  Profile.addUserId(builder, userIdOffset);
-  Profile.addDisplayName(builder, displayNameOffset);
-  Profile.addPreferredLanguage(builder, preferredLanguageOffset);
-  Profile.addTimeZone(builder, timeZoneOffset);
-  Profile.addHintBalance(builder, hintBalance);
-  Profile.addBlockChat(builder, blockChat);
-  Profile.addBlockFriendRequests(builder, blockFriendRequests);
-  Profile.addIsGuest(builder, isGuest);
-  Profile.addAwayStart(builder, awayStartOffset);
-  Profile.addAwayEnd(builder, awayEndOffset);
-  Profile.addNotificationsInAppOnly(builder, notificationsInAppOnly);
-  return Profile.endProfile(builder);
-}
 }