fix(i18n): give the tuning sweep the language it measures

4f2c9140fa made server() take the codes that decide which argos models the
deploy bakes, and updated the translate path. The tuning sweep calls the
same context manager and was left on the old one-argument form, so
`make i18n-tune` raised TypeError before it reached the server. It already
holds its target in `code`, the value it feeds to sample() and to the
readiness wait, so the sweep now deploys the pivot plus exactly the one
language it is about to measure instead of a server with nothing baked.

Nothing imports this module in tests and the repository runs no type
checker, so the arity drift passed ruff and the whole unit suite unseen.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

cli/build/i18n/tune.py

@@ -88,7 +88,7 @@ def tune(cpus: int, code: str) -> dict:
         for factor in LANE_FACTORS
     ]
     runs: dict[tuple[int, int], list[float]] = {pair: [] for pair in pairs}
-    with server(PROJECT_ROOT) as url:
+    with server(PROJECT_ROOT, [code]) as url:
         client = LibreTranslate(url, 1)
         client.wait(
             [code],