hub v0.118.0: the household's e-mails follow the household's language (R-558 Part A)

The hub has written every customer e-mail in Hungarian whatever the box was set
to. The box has published its language since controller v0.247.0; nothing read
it. Now it does.

Nothing an operator reads changes. The Hungarian mails are byte-identical, and
that is a diff rather than a reading: 56 goldens per language captured from
v0.117.0 BEFORE any string moved, and all 56 Hungarian ones pass unchanged after
every sentence was routed through the new bundle.

- internal/i18n: flat bundle, 79 keys, hu authoritative + hu fallback, ceiling 0.
- customerMessages/severityLabels are DERIVED from the bundle, so a sentence is
  written in one place and all 40+ tests that read those maps still work.
- Language order: last reported -> created-with -> hu. reports.language defaults
  to EMPTY, never hu: "never told us" is not "chose Hungarian".
- message_customer on POST /api/v1/event, additive and optional forever, for the
  sentences the box composes and the hub cannot translate.
- The bind page is per-language, and its `expired` state stays Hungarian: it is
  the state an unknown token lands in, so rendering a real English customer's
  token in English would make the LANGUAGE answer what the TEXT refuses to.

Two defects found inside the release:
- R-581: the newest report was picked by received_at, which has SECOND
  granularity, so same-second reports tied and the winner was arbitrary. Ordered
  by the autoincrement id now. GetCustomers() still has the shape - row open.
- R-582: the English copy-guard stems, ported word for word from Hungarian,
  convicted 141 honest sentences. The English claim is a phrase with a modal.

R-555 closed: the language allowlist entry is out of wire_contract_gate.py.
hub_copy_gate.py follows the sentences into the bundle - without that it would
have scanned four files that no longer hold any customer text and reported
success. Three new decoys incl. an innocent control.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0159rPz1ZhFKsS53msqPYxtS

documentation/architecture/10-localisation.md

@@ -119,7 +119,16 @@ the hub's e-mails follow.**
   `"language": "en"`, the three pages English; the hub's stored reports read no field (0.246.0), `hu`,
   `en` at 12:54:43Z, `hu` at 12:55:22Z after switching back; without `_csrf` → 403 and nothing changed
   (`audits/i18n-2026-09-17/live/README.md`).
-- **[DESIGN] Not built — slice 3:** the hub stores a per-customer language, renders it into
+- **[FACT] Slice 3 Part A, hub v0.118.0 (2026-09-18):** the hub READS the reported language and writes
+  the household's e-mails in it. `hub/internal/i18n` (79 keys, hu authoritative, hu fallback, missing
+  ceiling 0); 56 mail goldens captured from v0.117.0 BEFORE any string moved, and all 56 Hungarian
+  ones pass unchanged. `customerMessages`/`severityLabels` are derived from the bundle. Order: last
+  reported → `customer_configs.language` → `hu` (`Store.CustomerLanguage`). `message_customer` is
+  accepted on `POST /api/v1/event` for the box's own sentences. The bind page is per-language, with
+  `expired` pinned to Hungarian so the language cannot become the oracle the text refuses to be.
+  Full design: `05-hub-architecture.md` §15. **R-555 closed** — the `language` allowlist entry is out
+  of `wire_contract_gate.py` and the gate now checks the field for real.
+- **[DESIGN] Slice 3 Part A as planned — now built; the box half (Part B) is the remaining piece:** the hub stores a per-customer language, renders it into
   `controller.yaml` next to `customer.id/name/domain/email` (`hub/internal/configgen/configgen.go`),
   and the box uses it **only while the household has never chosen** (`settings.json` empty). The
   household's own choice always wins; the hub's e-mails follow the language the box **reports**, which