R-1254 (controller half): escrow claim/confirm outwait the agent (60 s); an unknown confirm outcome promises nothing

504 from the agent (it cannot learn which package the hub holds) or a failed call -> api.escrow.confirm_store_unknown
(hu+en); only 502 keeps 'your previous code still works'. Tests TestR1254_* red before the fix. Commit only.

controller/internal/i18n/locales/en.json

@@ -2672,6 +2672,7 @@
   "api.escrow.confirm_expired": "The time to type the new code back has run out — your previous code still works. Start the process again.",
   "api.escrow.confirm_lost": "The new code no longer waits for confirmation — your previous code still works. Start the process again.",
   "api.escrow.confirm_store_failed": "The new code could not be saved — your previous code still works. Try again.",
+  "api.escrow.confirm_store_unknown": "We cannot tell yet whether the new code was saved — the server did not answer in time. Keep both codes (the old one and the new one) and try again.",
   "api.escrow.confirm_words_mismatch": "The words do not match — check the code you wrote down.",
   "api.share.form_invalid": "Invalid form — reload the page.",
   "api.share.too_many_attempts": "Too many failed attempts, try again in 1 minute",