Update Supabase version and improve Keystatic's configurations

This commit updates the version of Supabase in multiple packages. It also introduces specificity to environment variables in Keystatic configuration and adds a method to create a 'KeyStatic' reader based on the storage kind. Furthermore, minor adjustments have been made to keep the environment variable names consistent.

apps/web/package.json

@@ -51,7 +51,7 @@
     "@makerkit/data-loader-supabase-nextjs": "^1.1.0",
     "@marsidev/react-turnstile": "^0.5.4",
     "@radix-ui/react-icons": "^1.3.0",
-    "@supabase/supabase-js": "^2.42.4",
+    "@supabase/supabase-js": "^2.42.5",
     "@tanstack/react-query": "5.29.2",
     "@tanstack/react-query-next-experimental": "^5.29.2",
     "@tanstack/react-table": "^8.16.0",
@@ -60,7 +60,7 @@
     "i18next": "^23.11.2",
     "i18next-resources-to-backend": "^1.2.1",
     "lucide-react": "^0.368.0",
-    "next": "14.3.0-canary.9",
+    "next": "14.3.0-canary.7",
     "next-sitemap": "^4.2.3",
     "next-themes": "0.3.0",
     "react": "18.2.0",