Renomme excalidraw-go en excalicloud

Module Go github.com/vblogio/excalicloud (imports internes mis à jour),
image Docker excalicloud:local, paquet npm excalicloud-frontend,
champ source des exports .excalidraw, README et THIRD_PARTY_NOTICES.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019MgtkAhkuqFbMAuTgTDeFh

frontend/package.json

@@ -1,5 +1,5 @@
 {
-  "name": "excalidraw-go-frontend",
+  "name": "excalicloud-frontend",
   "private": true,
   "version": "0.1.0",
   "type": "module",