chore: remove knip, husky and lint-staged

Drop the unused knip dead-code check and the husky+lint-staged pre-commit hook pipeline. All checks remain covered by the CI workflow (lint, typecheck, i18n, tests).

.gitea/workflows/ci.yaml

@@ -58,9 +58,6 @@ jobs:
             time pnpm test --maxWorkers=2
           fi
 
-      - name: Knip (unused files/exports)
-        run: pnpm knip
-
   # ─────────────────────────────────────────────
   # Docker build & deploy
   # Draait op de host (self-hosted) zodat Docker