Update license year to 2026

Author: seomin0610

i18n/en/docusaurus-theme-classic/footer.json

@@ -40,7 +40,7 @@
     "description": "The label of footer link with label=GitHub linking to https://github.com/SideStore"
   },
   "copyright": {
-    "message": "Copyright © 2025 SideStore, LLC. Built with Docusaurus.",
+    "message": "Copyright © 2026 SideStore, LLC. Built with Docusaurus.",
     "description": "The footer copyright"
   }
 }

i18n/it/docusaurus-theme-classic/footer.json

@@ -40,7 +40,7 @@
     "description": "The label of footer link with label=GitHub linking to https://github.com/SideStore"
   },
   "copyright": {
-    "message": "Copyright © 2025 SideStore, LLC. Built with Docusaurus.",
+    "message": "Copyright © 2026 SideStore, LLC. Built with Docusaurus.",
     "description": "The footer copyright"
   }
 }

i18n/ko/docusaurus-theme-classic/footer.json

@@ -40,7 +40,7 @@
     "description": "https://github.com/SideStore으로 연결되는 푸터 링크의 라벨"
   },
   "copyright": {
-    "message": "저작권 © 2025 SideStore, LLC. Docusaurus로 구축됨.",
+    "message": "저작권 © 2026 SideStore, LLC. Docusaurus로 구축됨.",
     "description": "저작권 푸터"
   }
 }