fix: resolve CI failures — Node 20+, exclude scanner-worker from build

- Update GitHub Actions workflows to Node 20/22 (ESLint 10 requires Node 20+)
- Exclude scanner-worker/ from frontend tsconfig and .dockerignore
- Update engines to require Node >= 20

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

frontend/.dockerignore

@@ -2,3 +2,4 @@ node_modules
 npm-debug.log
 .env
 .git
+scanner-worker

frontend/tsconfig.json

@@ -23,5 +23,5 @@
     }
   },
   "include": ["next-env.d.ts", "**/*.ts", "**/*.tsx", ".next/types/**/*.ts"],
-  "exclude": ["node_modules"]
+  "exclude": ["node_modules", "scanner-worker"]
 }