Normalize

Run text through the TN pipeline (admin testing surface).

The admin web app uses this to test post-override rules: normalize, diff, add a rule, /v1/post-overrides/reload, normalize again. The LM path is used when wired; on LM failure the heuristic path answers instead so the testing surface stays available (matching v1). Post-overrides apply on both paths via the runtime's wrapped normalizers.