feat(game): race exit warnings in the turn report (#12)

Surface the inactivity-removal countdown the rules promise but the
engine never reported. A race within five turns of being auto-removed
for inactivity gets a personal warning in its own report; every race
within three turns is listed publicly to all participants.

- model: Report.PersonalExitWarning + RacesLeavingSoon ([]RaceExitNotice)
- fbs: RaceExitNotice table + Report.personal_exit_warning /
  races_leaving_soon (regenerated Go + TS bindings)
- transcoder: encode/decode both fields
- engine: ReportExitWarnings fills the recipient's TTL (1..5) and lists
  other non-extinct races with TTL 1..3, excluding the recipient itself
- ui: danger-styled personal banner + "races leaving soon" section
  (hidden when empty), wired into the report view, EN/RU i18n
- docs: rules.txt report-section list, FUNCTIONAL.md 6.4 + RU mirror

Voluntary quit and idle timeout share the TTL countdown and are not
distinguished, per the agreed scope.

ui/frontend/tests/e2e/fixtures/report-fbs.ts

@@ -26,6 +26,7 @@ import {
 	OtherScience,
 	OthersShipClass,
 	Player,
+	RaceExitNotice,
 	Report,
 	Route,
 	RouteEntry,
@@ -139,6 +140,11 @@ export interface ShipProductionFixture {
 	free?: number;
 }
 
+export interface RaceExitNoticeFixture {
+	race: string;
+	turnsLeft: number;
+}
+
 export interface ReportFixture {
 	turn: number;
 	mapWidth?: number;
@@ -159,6 +165,8 @@ export interface ReportFixture {
 	battles?: BattleSummaryFixture[];
 	bombings?: BombingFixture[];
 	shipProductions?: ShipProductionFixture[];
+	personalExitWarning?: number;
+	racesLeavingSoon?: RaceExitNoticeFixture[];
 }
 
 export function buildReportPayload(fixture: ReportFixture): Uint8Array {
@@ -356,6 +364,14 @@ export function buildReportPayload(fixture: ReportFixture): Uint8Array {
 		return ShipProduction.endShipProduction(builder);
 	});
 
+	const racesLeavingSoonOffsets = (fixture.racesLeavingSoon ?? []).map((n) => {
+		const race = builder.createString(n.race);
+		RaceExitNotice.startRaceExitNotice(builder);
+		RaceExitNotice.addRace(builder, race);
+		RaceExitNotice.addTurnsLeft(builder, n.turnsLeft);
+		return RaceExitNotice.endRaceExitNotice(builder);
+	});
+
 	const localVec =
 		localOffsets.length === 0
 			? null
@@ -404,6 +420,10 @@ export function buildReportPayload(fixture: ReportFixture): Uint8Array {
 		shipProductionOffsets.length === 0
 			? null
 			: Report.createShipProductionVector(builder, shipProductionOffsets);
+	const racesLeavingSoonVec =
+		racesLeavingSoonOffsets.length === 0
+			? null
+			: Report.createRacesLeavingSoonVector(builder, racesLeavingSoonOffsets);
 	// Phase 27 — `battle` carries `BattleSummary` tables, each with
 	// an inline `id:UUID` struct plus `planet` and `shots` slots.
 	const battleVec = (() => {
@@ -462,6 +482,10 @@ export function buildReportPayload(fixture: ReportFixture): Uint8Array {
 	if (bombingVec !== null) Report.addBombing(builder, bombingVec);
 	if (shipProductionVec !== null)
 		Report.addShipProduction(builder, shipProductionVec);
+	if (fixture.personalExitWarning !== undefined)
+		Report.addPersonalExitWarning(builder, fixture.personalExitWarning);
+	if (racesLeavingSoonVec !== null)
+		Report.addRacesLeavingSoon(builder, racesLeavingSoonVec);
 	const reportOff = Report.endReport(builder);
 	builder.finish(reportOff);
 	return builder.asUint8Array();