feat: photo-search, system settings, ROADMAP

- PhotoSearchModal: Yandex photo-search с профилями доменов
- SystemSettings: управление app_settings (admin-only, /system)
- ROADMAP.md: актуальный план фич P1-P10
- Header, ChannelView, session: поддержка is_admin

app/api/photo-search/profiles/route.js

@@ -0,0 +1,14 @@
+import { NextResponse } from 'next/server';
+import { requireUser } from '@/lib/session';
+import { engine } from '@/lib/engine';
+
+export async function GET() {
+  const user = await requireUser();
+  if (!user) return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
+  try {
+    const data = await engine.photoSearchProfiles();
+    return NextResponse.json(data);
+  } catch (err) {
+    return NextResponse.json({ error: err.message }, { status: err.status || 500 });
+  }
+}