fix(scheduler,i18n): a failure a job names reads in the reader's language

The audit log showed a failed RSS poll as the server's English sentence
under a Hungarian UI. A job can now raise progress.JobFailed(reason,
message, **params): the scheduler stores the reason and params as the
run's data (dashboard, manual-run notice, audit row) beside the English
line, and the client renders scheduler.failure.<reason>. The RSS outage
names its first channel and the reason code (HTTP 404 vs unreachable).
An upstream's own error text stays as raised (diagnostic).

frontend/src/lib/jobResult.ts

@@ -38,10 +38,30 @@ export function jobResultText(t: TFunction, result: JobResult, lang: string): st
     .join(" · ");
 }
 
+/** A failure the job named (the server's `progress.JobFailed`: `{failure: <reason>, …params}`) in the
+ *  reader's language (E31); null for any other failure, which keeps the upstream's own text. */
+export function jobFailureText(t: TFunction, result: unknown, lang: string): string | null {
+  if (!result || typeof result !== "object") return null;
+  const { failure, ...params } = result as Record<string, unknown>;
+  if (typeof failure !== "string") return null;
+  const values: Record<string, string> = {};
+  for (const [k, v] of Object.entries(params))
+    values[k] = typeof v === "number" ? formatNumber(v, lang) : String(v);
+  if (typeof params.cause === "string") values.cause = rssCause(t, params.cause);
+  return t(`scheduler.failure.${failure}`, { ...values, defaultValue: "" }) || null;
+}
+
+/** Why a feed did not answer, from the poll's reason code (`http_404`, `transport`, …). */
+function rssCause(t: TFunction, cause: string): string {
+  const http = /^http_(\d+)$/.exec(cause);
+  if (http) return t("scheduler.rssCause.http", { status: http[1] });
+  return t(`scheduler.rssCause.${cause}`, { defaultValue: cause });
+}
+
 /** What a job run said, as the inbox notice and the audit row both show it (E30): a title naming the job
  *  and how the run ended, and its result in the reader's language — from the data when it rode along,
- *  else read back from the English one-liner. A skipped run names only why; a failed run keeps the
- *  upstream's own error text (it is diagnostic). */
+ *  else read back from the English one-liner. A skipped run names only why; a failed run says the
+ *  failure the job named (`jobFailureText`, E31), else keeps the upstream's own text (diagnostic). */
 export function jobRunText(
   t: TFunction,
   run: { job_id: string; status?: unknown; summary?: unknown; result?: unknown },
@@ -65,10 +85,12 @@ export function jobRunText(
   }
   // A skipped run's title already says "skipped": its body is only the reason, not "skipped: <reason>".
   const reason = run.status === "skipped" ? onlySkipReason(result) : null;
+  const failure = run.status === "error" ? jobFailureText(t, run.result, lang) : null;
   return {
     title: t(titleKey, { job }),
-    body:
-      reason !== null
+    body: failure
+      ? failure
+      : reason !== null
         ? t(`scheduler.skip.${vocabKey(reason)}`, { defaultValue: reason })
         : result
           ? jobResultText(t, result, lang)