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")}
-                    {session.endedAt ? ` – ${new Date(session.endedAt).toLocaleString("tr-TR")}` : " (devam ediyor)"}
+                    {formatTr(session.startedAt)}
+                    {session.endedAt ? ` – ${formatTr(session.endedAt)}` : " (devam ediyor)"}
                   </span>
                   <Badge variant="muted">{session.totalSegments} segment</Badge>
                 </CardHeader>