feat: implement and deploy blind_chess MVP

- pnpm workspace: shared/server/client packages
- Server: Fastify+ws, chess.js, FSM (touch-move + hierarchy),
  per-player view filter, zod validation, rate limiting, grace-window
  disconnect handling
- Client: Svelte 5 + Vite, click-to-move board, moderator panel,
  promotion/draw dialogs
- Shared: protocol types, ModeratorText enum, geometricMoves helper
  (provably zero opponent-info leak)
- 43 tests pass (21 shared, 22 server incl. 4 real-WS integration)
- Deploy: CT 690 on node-241 (192.168.0.245), systemd-managed,
  Caddy block for chess.sethpc.xyz
- Live at https://chess.sethpc.xyz

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/server/src/state.ts

@@ -0,0 +1,58 @@
+import type { Chess } from 'chess.js';
+import type { WebSocket } from 'ws';
+import type {
+  Announcement,
+  Color,
+  EndReason,
+  GameId,
+  GameStatus,
+  Mode,
+  PieceType,
+  PlayerToken,
+  PromotionType,
+  Square,
+} from '@blind-chess/shared';
+
+export interface MoveRecord {
+  ply: number;
+  by: Color;
+  from: Square;
+  to: Square;
+  san: string;
+  capturedPieceType?: PieceType;
+  promotion?: PromotionType;
+  flags: { castle?: 'k' | 'q'; enPassant?: boolean; check?: boolean; mate?: boolean };
+  at: number;
+}
+
+export interface PlayerSlot {
+  token: PlayerToken;
+  socket: WebSocket | null;
+  joinedAt: number;
+  rateBucket: { tokens: number; last: number };
+}
+
+export interface Game {
+  id: GameId;
+  mode: Mode;
+  highlightingEnabled: boolean;
+  status: GameStatus;
+  createdAt: number;
+  finishedAt?: number;
+  endReason?: EndReason;
+  winner?: Color | null;
+
+  chess: Chess;
+  moveHistory: MoveRecord[];
+  announcements: Announcement[];
+
+  players: { w: PlayerSlot | null; b: PlayerSlot | null };
+
+  armed: { color: Color; from: Square } | null;
+  drawOffer: { from: Color; at: number } | null;
+  disconnectAt: { w?: number; b?: number };
+}
+
+export const RATE_LIMIT = { capacity: 20, refillPerSec: 10 };
+export const GRACE_MS = 5 * 60 * 1000;
+export const PRUNE_AFTER_FINISHED_MS = 30 * 60 * 1000;