fix(ui): a write that fails says what failed and why, wherever it fails

`req` opens its blocking dialog for 400/409/422/5xx only. A 403/404/429 was left to the caller and a
502-504 or lost connection got just the self-clearing connection notice, so 34 mutations without a
reporting onError and 15 direct api writes with a bare or missing catch failed in silence: a hidden
channel that snapped back, a share link that never revoked, a confirmed account delete that ended
with nothing said.

- lib/queryClient: one MutationCache reporter. react-query awaits it BEFORE the mutation's own
  onError, so it waits a task and skips a failure the site already reported; the toast title comes
  from `meta.failTitle`, `meta.errorShownInline` opts out.
- notifyActionError: title names WHAT failed, the line under it says WHY (`failureReason`: a
  structured localized detail, else the status). It marks the error reported (`markReported`), so
  nothing reports one failure twice; `notifyKnownFailure` for a site's own specific sentence.
- Every silent site named (45 new HU/EN titles, 4 reasons). Stale "the global dialog shows it"
  comments corrected on the job actions, channel block, Plex sync, cookies, download enqueue,
  account delete and usePref.
- Channels passed the tag hook's channel id to the reporter as the error; the tag and priority hooks
  now report themselves, with the real error.
- A contract test keeps every useMutation naming its failure; CLAUDE.md gains the pattern row.
- history.dom.test: the "navigates only once the entries are back" assertion raced an async act's
  macrotask flush (1 in 5 runs); it now asserts from a later popstate listener.

frontend/src/components/SyncStatus.tsx

@@ -4,6 +4,7 @@ import { qk } from "../lib/queryKeys";
 import { useTranslation } from "react-i18next";
 import { CheckCircle2, Clock, Database, History, Loader2, Pause, Play } from "lucide-react";
 import { api, type MyStatus } from "../lib/api";
+import { notifyActionError } from "../lib/actionErrors";
 import { formatViews } from "../lib/format";
 import { PopoverSurface, useAnchoredPopover } from "./ui/AnchoredPopover";
 
@@ -53,6 +54,11 @@ export default function SyncStatus({
   const toggle = useMutation({
     mutationFn: () => (data?.paused ? api.resumeSync() : api.pauseSync()),
     onSuccess: () => qc.invalidateQueries({ queryKey: qk.myStatus() }),
+    onError: (e) =>
+      notifyActionError(
+        e,
+        t(data?.paused ? "errors.writeFailed.syncResume" : "errors.writeFailed.syncPause"),
+      ),
   });
 
   if (!data) return null;