feat: Vollständiges Rebranding zu MiChess, Copyright Tom Misch

- Alle @chessu/ → @michess/ (Package-Namen und Imports)
- Theme-Namen chessuDark/Light → michessDark/Light
- Alle Display-Texte: chessu/Michess → MiChess
- Autor: dotnize → Tom Misch
- Copyright: Nathaniel Tampus → Tom Misch
- README komplett neu (Deutsch, MiChess-spezifisch)
- CONTRIBUTING.md neu
- FUNDING.yml + CODE_OF_CONDUCT.md entfernt
- Fork-Hinweis auf chessu bleibt im README erhalten (MIT-Pflicht)
- pnpm-lock.yaml entfernt (wird beim Build neu generiert)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

client/src/components/game/GamePage.tsx

@@ -15,7 +15,7 @@ import { SessionContext } from "@/context/session";
 import { useContext, useEffect, useReducer, useRef, useState } from "react";
 
 import type { Message } from "@/types";
-import type { Game } from "@chessu/types";
+import type { Game } from "@michess/types";
 
 import type { Move, Square } from "chess.js";
 import { Chess } from "chess.js";
@@ -149,9 +149,9 @@ export default function GamePage({ initialLobby }: { initialLobby: Game }) {
     if (lobby.side === "s" || !lobby.white?.id || !lobby.black?.id) return;
 
     if (!lobby.endReason && lobby.side === lobby.actualGame.turn()) {
-      document.title = "(your turn) chessu";
+      document.title = "(your turn) MiChess";
     } else {
-      document.title = "chessu";
+      document.title = "MiChess";
     }
   }