Fix ESLint configuration for Docker build

- Remove ignoreDuringBuilds from eslintConfig in package.json (invalid)
- Add eslint.ignoreDuringBuilds to next.config.js (correct location)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

package.json

@@ -187,7 +187,6 @@
     "importOrderSortSpecifiers": true
   },
   "eslintConfig": {
-    "ignoreDuringBuilds": true,
     "extends": [
       "next",
       "eslint:recommended",