fix(i18n): disable createMessagesDeclaration to fix typecheck

The auto-generated en.d.json.ts was stale (missing beszel keys),
causing 67 TS2345 errors. Additionally, with ~2,367 leaf keys at
depth 10, the generated declaration triggers TS type complexity
limits (known next-intl issue #2296).

Disable the feature in next.config.ts, delete the stale file,
and remove its .gitignore entry. Key/namespace validation is
preserved via raw JSON import types.

apps/nextjs/next.config.ts

@@ -10,9 +10,6 @@ import createNextIntlPlugin from "next-intl/plugin";
 
 // Package path does not work... so we need to use relative path
 const withNextIntl = createNextIntlPlugin({
-  experimental: {
-    createMessagesDeclaration: "../../packages/translation/src/lang/en.json",
-  },
   requestConfig: "../../packages/translation/src/request.ts",
 });