feat: монорепо миграция, Discover/SearxNG улучшения

- Миграция на монорепозиторий (apps/frontend, apps/chat-service, etc.)
- Discover: проверка SearxNG, понятное empty state при ненастроенном поиске
- searxng.ts: валидация URL, проверка JSON-ответа, авто-добавление http://
- docker/searxng-config: настройки для JSON API SearxNG

Co-authored-by: Cursor <cursoragent@cursor.com>

apps/frontend/src/app/api/providers/route.ts

@@ -0,0 +1,74 @@
+import ModelRegistry from '@/lib/models/registry';
+import { NextRequest } from 'next/server';
+
+export const GET = async (req: Request) => {
+  try {
+    const registry = new ModelRegistry();
+
+    const activeProviders = await registry.getActiveProviders();
+
+    const filteredProviders = activeProviders.filter((p) => {
+      return !p.chatModels.some((m) => m.key === 'error');
+    });
+
+    return Response.json(
+      {
+        providers: filteredProviders,
+      },
+      {
+        status: 200,
+      },
+    );
+  } catch (err) {
+    console.error('An error occurred while fetching providers', err);
+    return Response.json(
+      {
+        message: 'An error has occurred.',
+      },
+      {
+        status: 500,
+      },
+    );
+  }
+};
+
+export const POST = async (req: NextRequest) => {
+  try {
+    const body = await req.json();
+    const { type, name, config } = body;
+
+    if (!type || !name || !config) {
+      return Response.json(
+        {
+          message: 'Missing required fields.',
+        },
+        {
+          status: 400,
+        },
+      );
+    }
+
+    const registry = new ModelRegistry();
+
+    const newProvider = await registry.addProvider(type, name, config);
+
+    return Response.json(
+      {
+        provider: newProvider,
+      },
+      {
+        status: 200,
+      },
+    );
+  } catch (err) {
+    console.error('An error occurred while creating provider', err);
+    return Response.json(
+      {
+        message: 'An error has occurred.',
+      },
+      {
+        status: 500,
+      },
+    );
+  }
+};