refactor(i18n,format): translate ETA strings; consolidate time/duration formatters

- formatEta was hardcoded English (violated the trilingual rule) -> time.eta.* keys
  in EN/HU/DE; Scheduler's countdown 'now' likewise.
- relativeFromMs added to format.ts; NotificationsPanel drops its duplicate
  relativeTime/relativeFromMs and the now-orphaned notifications.time.* keys.
- Channels' fmtTotalDuration moved to format.ts as formatTotalHours.

frontend/src/components/Channels.tsx

@@ -15,7 +15,7 @@ import {
 } from "lucide-react";
 import { api, HttpError, type ManagedChannel, type Tag } from "../lib/api";
 import { useDismiss } from "../lib/useDismiss";
-import { formatEta, formatViews, relativeTime } from "../lib/format";
+import { formatEta, formatTotalHours, formatViews, relativeTime } from "../lib/format";
 import { notify } from "../lib/notifications";
 import Tooltip from "./Tooltip";
 import DataTable, { type Column } from "./DataTable";
@@ -28,13 +28,6 @@ export type ChannelsView = "subscribed" | "discovery";
 
 export type ChannelStatusFilter = "all" | "needs_full" | "fully_synced" | "hidden";
 
-// Compact total-duration label for a whole channel (hours-scale, so H:MM:SS would be huge).
-function fmtTotalDuration(sec: number): string {
-  if (!sec) return "—";
-  const h = Math.round(sec / 3600);
-  return h >= 1 ? `${h.toLocaleString()} h` : `${Math.max(1, Math.round(sec / 60))} m`;
-}
-
 const STATUS_FILTERS: { id: ChannelStatusFilter; labelKey: string }[] = [
   { id: "all", labelKey: "channels.filters.all" },
   { id: "needs_full", labelKey: "channels.filters.needsFull" },
@@ -287,7 +280,7 @@ export default function Channels({
       nowrap: true,
       sortable: true,
       sortValue: (c) => c.total_duration_seconds,
-      render: (c) => <span className="text-muted tabular-nums">{fmtTotalDuration(c.total_duration_seconds)}</span>,
+      render: (c) => <span className="text-muted tabular-nums">{formatTotalHours(c.total_duration_seconds)}</span>,
     },
     {
       key: "types",

frontend/src/components/NotificationsPanel.tsx

@@ -19,7 +19,7 @@ import {
   type VideoHiddenMeta,
   type VideoWatchedMeta,
 } from "../lib/notifications";
-import { channelYouTubeUrl } from "../lib/format";
+import { channelYouTubeUrl, relativeFromMs, relativeTime } from "../lib/format";
 import type { Page } from "../lib/urlState";
 import { LEVEL_STYLE } from "./Toaster";
 
@@ -29,22 +29,6 @@ import { LEVEL_STYLE } from "./Toaster";
 // there's one indicator and one place to look. Transient toasts still pop via the Toaster.
 const POLL_MS = 8000;
 
-function relativeTime(iso: string | null, t: (k: string, o?: any) => string): string {
-  if (!iso) return "";
-  return relativeFromMs(new Date(iso).getTime(), t);
-}
-
-function relativeFromMs(ms: number, t: (k: string, o?: any) => string): string {
-  const secs = Math.max(0, Math.round((Date.now() - ms) / 1000));
-  // Reuse the bell's relative-time strings (notifications.time.*) — same format, no dupes.
-  if (secs < 60) return t("notifications.time.justNow");
-  const mins = Math.round(secs / 60);
-  if (mins < 60) return t("notifications.time.minutes", { count: mins });
-  const hours = Math.round(mins / 60);
-  if (hours < 24) return t("notifications.time.hours", { count: hours });
-  return t("notifications.time.days", { count: Math.round(hours / 24) });
-}
-
 export default function NotificationsPanel({
   filters,
   setFilters,
@@ -253,7 +237,7 @@ function NotificationRow({
         <div className="flex items-baseline gap-2">
           <span className="font-medium text-sm">{title}</span>
           <span className="text-[11px] text-muted shrink-0">
-            {relativeTime(n.created_at, t)}
+            {relativeTime(n.created_at)}
           </span>
         </div>
         {body && <div className="text-sm text-muted mt-0.5">{body}</div>}
@@ -338,7 +322,7 @@ function ClientActivityRow({
         {n.title && <div className="text-sm font-semibold">{n.title}</div>}
         <div className="text-sm break-words">{n.message}</div>
         <div className="flex items-center gap-2 mt-0.5">
-          <span className="text-[11px] text-muted">{relativeFromMs(n.ts, t)}</span>
+          <span className="text-[11px] text-muted">{relativeFromMs(n.ts)}</span>
           {needsAction && (
             <span className="text-[10px] uppercase tracking-wide font-semibold text-accent">
               {t("notifications.actionNeeded")}

frontend/src/components/Scheduler.tsx

@@ -1,5 +1,6 @@
 import { useEffect, useState } from "react";
 import { useTranslation } from "react-i18next";
+import i18n from "../i18n";
 import { useMutation, useQueryClient } from "@tanstack/react-query";
 import {
   Activity,
@@ -31,7 +32,7 @@ function secsUntil(iso: string | null): number | null {
 }
 
 function fmtCountdown(s: number): string {
-  if (s <= 0) return "now";
+  if (s <= 0) return i18n.t("time.eta.now");
   if (s < 60) return `${s}s`;
   const m = Math.floor(s / 60);
   if (m < 60) return `${m}m ${s % 60}s`;