fix: panelde saatler 3 saat geri gösteriliyordu (sunucu UTC, Türkiye UTC+3)

.toLocaleString("tr-TR") tarih formatını Türkçe yapıyor ama saat değerini
hâlâ sunucunun sistem saat dilimiyle (Coolify/Hetzner container'ı UTC)
hesaplıyordu. Tüm tarih gösterimleri artık ortak formatTr() helper'ı
üzerinden timeZone: "Europe/Istanbul" ile sabitleniyor.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/frontend/app/channels/[id]/page.tsx

@@ -2,6 +2,7 @@ import { notFound } from "next/navigation";
 import Link from "next/link";
 import { prisma } from "@streamclipper/db";
 import { fetchChannelStatuses } from "../../../lib/apiDaemon";
+import { formatTr } from "../../../lib/formatDate";
 import {
   deleteRawSegment,
   deleteCandidateSegment,
@@ -113,7 +114,7 @@ export default async function ChannelDetailPage({ params }: { params: Promise<{
         <CardContent className="flex flex-col gap-3">
           <p className="font-mono-num text-xs text-muted-foreground">
             Aktif: {channel.isActive ? "evet" : "hayır"} · Son kontrol:{" "}
-            {channel.lastCheckedAt ? new Date(channel.lastCheckedAt).toLocaleString("tr-TR") : "—"}
+            {channel.lastCheckedAt ? formatTr(channel.lastCheckedAt) : "—"}
           </p>
 
           <form
@@ -157,7 +158,7 @@ export default async function ChannelDetailPage({ params }: { params: Promise<{
                   son poll hatası
                 </Badge>
                 <span className="font-mono-num text-xs text-muted-foreground">
-                  {new Date(status.lastPollError.at).toLocaleString("tr-TR")}
+                  {formatTr(status.lastPollError.at)}
                 </span>
               </div>
               <pre className="font-mono-num whitespace-pre-wrap rounded-md border border-border bg-background/60 p-3 text-[0.7rem] text-muted-foreground">
@@ -199,8 +200,8 @@ export default async function ChannelDetailPage({ params }: { params: Promise<{
               <Card key={session.id}>
                 <CardHeader className="flex-row items-center justify-between">
                   <span className="font-mono-num text-xs text-muted-foreground">
-                    {new Date(session.startedAt).toLocaleString("tr-TR")}
+                    {formatTr(session.startedAt)}
-                    {session.endedAt ? ` – ${new Date(session.endedAt).toLocaleString("tr-TR")}` : " (devam ediyor)"}
+                    {session.endedAt ? ` – ${formatTr(session.endedAt)}` : " (devam ediyor)"}
                   </span>
                   <Badge variant="muted">{session.totalSegments} segment</Badge>
                 </CardHeader>

apps/frontend/app/page.tsx

@@ -2,6 +2,7 @@ import Link from "next/link";
 import { prisma } from "@streamclipper/db";
 import { addChannel, toggleChannelActive, toggleAllChannels, checkChannelNow } from "./actions";
 import { fetchChannelStatuses } from "../lib/apiDaemon";
+import { formatTr } from "../lib/formatDate";
 import { Button } from "@/components/ui/button";
 import { Input } from "@/components/ui/input";
 import { Badge } from "@/components/ui/badge";
@@ -94,7 +95,7 @@ export default async function DashboardPage() {
                           {status?.lastPollError && (
                             <Badge
                               variant="err"
-                              title={`${new Date(status.lastPollError.at).toLocaleString("tr-TR")} — ${status.lastPollError.message}`}
+                              title={`${formatTr(status.lastPollError.at)} — ${status.lastPollError.message}`}
                             >
                               hata
                             </Badge>
@@ -102,7 +103,7 @@ export default async function DashboardPage() {
                         </div>
                       </TableCell>
                       <TableCell className="font-mono-num text-xs text-muted-foreground">
-                        {c.lastCheckedAt ? new Date(c.lastCheckedAt).toLocaleString("tr-TR") : "—"}
+                        {c.lastCheckedAt ? formatTr(c.lastCheckedAt) : "—"}
                       </TableCell>
                       <TableCell>
                         <div className="flex justify-end gap-1.5">

apps/frontend/app/segments/page.tsx

@@ -1,5 +1,6 @@
 import { prisma } from "@streamclipper/db";
 import { deleteRawSegment, deleteCandidateSegment, retryRender, cancelRender } from "../actions";
+import { formatTr } from "../../lib/formatDate";
 import { ConfirmButton } from "../components/ConfirmButton";
 import { Button } from "@/components/ui/button";
 import { Badge, type badgeVariants } from "@/components/ui/badge";
@@ -46,7 +47,7 @@ export default async function SegmentsPage() {
                 <div>
                   <span className="font-mono-num text-xs text-muted-foreground">{segment.filePath}</span>
                   <p className="font-mono-num text-xs text-muted-foreground">
-                    {segment.duration}sn · {new Date(segment.startedAt).toLocaleString("tr-TR")}
+                    {segment.duration}sn · {formatTr(segment.startedAt)}
                   </p>
                 </div>
                 <Badge variant={STATUS_BADGE[segment.status] ?? "muted"}>{segment.status}</Badge>

apps/frontend/app/settings/page.tsx

@@ -1,5 +1,6 @@
 import { prisma } from "@streamclipper/db";
 import { updateYtdlpCookies, updateSystemSettings, updateNotificationPrefs, updateSttEnabled } from "../actions";
+import { formatTr } from "../../lib/formatDate";
 import { Button } from "@/components/ui/button";
 import { Input } from "@/components/ui/input";
 import { Label } from "@/components/ui/label";
@@ -38,7 +39,7 @@ export default async function SettingsPage() {
         <CardHeader className="flex-row items-center justify-between">
           <CardTitle className="text-sm font-medium text-muted-foreground">YouTube Cookie&apos;leri</CardTitle>
           <span className="font-mono-num text-xs text-muted-foreground">
-            {setting ? `son güncelleme: ${setting.updatedAt.toLocaleString("tr-TR")}` : "hiç ayarlanmadı"}
+            {setting ? `son güncelleme: ${formatTr(setting.updatedAt)}` : "hiç ayarlanmadı"}
           </span>
         </CardHeader>
         <CardContent className="flex flex-col gap-3">

apps/frontend/app/users/page.tsx

@@ -1,6 +1,7 @@
 import { prisma } from "@streamclipper/db";
 import { getSession } from "../../lib/auth";
 import { addUser, deleteUser } from "./actions";
+import { formatTr } from "../../lib/formatDate";
 import { ConfirmButton } from "../components/ConfirmButton";
 import { Button } from "@/components/ui/button";
 import { Input } from "@/components/ui/input";
@@ -56,7 +57,7 @@ export default async function UsersPage() {
                     )}
                   </TableCell>
                   <TableCell className="font-mono-num text-xs text-muted-foreground">
-                    {u.createdAt.toLocaleString("tr-TR")}
+                    {formatTr(u.createdAt)}
                   </TableCell>
                   <TableCell className="text-right">
                     {u.id !== session?.sub && users.length > 1 && (

apps/frontend/lib/formatDate.ts

@@ -0,0 +1,10 @@
+/**
+ * Server (Coolify/Hetzner) runs in UTC, but the panel is used from Turkey
+ * (UTC+3, no DST since 2016) — `.toLocaleString("tr-TR")` alone formats
+ * with tr-TR conventions but still uses the *server's* timezone for the
+ * actual time value, which was showing everything 3h behind. Always pin
+ * the timezone explicitly instead of relying on the runtime's default.
+ */
+export function formatTr(date: Date | string): string {
+  return new Date(date).toLocaleString("tr-TR", { timeZone: "Europe/Istanbul" });
+}