fix(lint): exempt next-env.d.ts triple-slash + declare globalEnv vars

next-env.d.ts is a generated file using triple-slash references that
TypeScript requires. ESLint exemption added in apps/web-next config only.
Also declare CI, DATABASE_URL, PAYLOAD_SECRET, NODE_ENV in turbo.json
globalEnv so turbo/no-undeclared-env-vars stops warning.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/web-next/eslint.config.js

@@ -1,3 +1,11 @@
 import baseConfig from "@repo/eslint-config/base";
 
-export default baseConfig;
+export default [
+  ...baseConfig,
+  {
+    files: ["next-env.d.ts"],
+    rules: {
+      "@typescript-eslint/triple-slash-reference": "off",
+    },
+  },
+];