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>

server/src/controllers/auth.controller.ts

@@ -1,4 +1,4 @@
-import type { User } from "@chessu/types";
+import type { User } from "@michess/types";
 import { hash, verify } from "argon2";
 import type { Request, Response } from "express";
 import xss from "xss";

server/src/controllers/games.controller.ts

@@ -1,4 +1,4 @@
-import type { Game, User } from "@chessu/types";
+import type { Game, User } from "@michess/types";
 import type { Request, Response } from "express";
 import { nanoid } from "nanoid";