feat(game): void unreplayable games as a draw instead of erroring

A committed move that becomes illegal under a tightened rule (the single-word
connectivity fix) makes engine replay fail, which left such games unopenable —
an empty screen and an 'illegal play' error. Now the first open closes the game
gracefully as a draw (engine.EndAborted -> end_reason 'aborted', no winner),
preserves the journal, and surfaces an impersonal organizer note at the end of
the move history and in the GCG export.

- engine: EndAborted + Abort() (draw, no rack adjustment; winner -1).
- service: replay aborts on ErrIllegalPlay; liveGame persists the void once
  (lazy, on open); GameState re-reads for the settled view.
- store: VoidGame finishes the game and stamps a draw without a journal row.
- migration 00002: allow end_reason 'aborted'.
- ui: organizer note under the history grid; i18n en/ru.
- docs: ARCHITECTURE 6/9.1, FUNCTIONAL(+ru), PRERELEASE MW3.

backend/internal/postgres/migrations/00002_aborted_end_reason.sql

@@ -0,0 +1,16 @@
+-- +goose Up
+-- Allow end_reason = 'aborted': a game whose journal can no longer be reconstructed (a
+-- recorded move became illegal under tightened rules) is closed as a draw rather than left
+-- unopenable. See engine.EndAborted and Service.voidGame.
+SET search_path = backend, pg_catalog;
+ALTER TABLE games DROP CONSTRAINT games_end_reason_chk;
+ALTER TABLE games ADD CONSTRAINT games_end_reason_chk CHECK (
+    end_reason IS NULL OR end_reason IN ('out_of_tiles', 'scoreless', 'resign', 'timeout', 'aborted')
+);
+
+-- +goose Down
+SET search_path = backend, pg_catalog;
+ALTER TABLE games DROP CONSTRAINT games_end_reason_chk;
+ALTER TABLE games ADD CONSTRAINT games_end_reason_chk CHECK (
+    end_reason IS NULL OR end_reason IN ('out_of_tiles', 'scoreless', 'resign', 'timeout')
+);