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/components/EmptyChatMessageInput.tsx

@@ -0,0 +1,88 @@
+import { ArrowRight } from 'lucide-react';
+import { useEffect, useRef, useState } from 'react';
+import TextareaAutosize from 'react-textarea-autosize';
+import Sources from './MessageInputActions/Sources';
+import Optimization from './MessageInputActions/Optimization';
+import Attach from './MessageInputActions/Attach';
+import { useChat } from '@/lib/hooks/useChat';
+import ModelSelector from './MessageInputActions/ChatModelSelector';
+
+const EmptyChatMessageInput = () => {
+  const { sendMessage } = useChat();
+
+  /* const [copilotEnabled, setCopilotEnabled] = useState(false); */
+  const [message, setMessage] = useState('');
+
+  const inputRef = useRef<HTMLTextAreaElement | null>(null);
+
+  useEffect(() => {
+    const handleKeyDown = (e: KeyboardEvent) => {
+      const activeElement = document.activeElement;
+
+      const isInputFocused =
+        activeElement?.tagName === 'INPUT' ||
+        activeElement?.tagName === 'TEXTAREA' ||
+        activeElement?.hasAttribute('contenteditable');
+
+      if (e.key === '/' && !isInputFocused) {
+        e.preventDefault();
+        inputRef.current?.focus();
+      }
+    };
+
+    document.addEventListener('keydown', handleKeyDown);
+
+    inputRef.current?.focus();
+
+    return () => {
+      document.removeEventListener('keydown', handleKeyDown);
+    };
+  }, []);
+
+  return (
+    <form
+      onSubmit={(e) => {
+        e.preventDefault();
+        sendMessage(message);
+        setMessage('');
+      }}
+      onKeyDown={(e) => {
+        if (e.key === 'Enter' && !e.shiftKey) {
+          e.preventDefault();
+          sendMessage(message);
+          setMessage('');
+        }
+      }}
+      className="w-full"
+    >
+      <div className="flex flex-col bg-light-secondary dark:bg-dark-secondary px-3 pt-5 pb-3 rounded-2xl w-full border border-light-200 dark:border-dark-200 shadow-sm shadow-light-200/10 dark:shadow-black/20 transition-all duration-200 focus-within:border-light-300 dark:focus-within:border-dark-300">
+        <TextareaAutosize
+          ref={inputRef}
+          value={message}
+          onChange={(e) => setMessage(e.target.value)}
+          minRows={2}
+          className="px-2 bg-transparent placeholder:text-[15px] placeholder:text-black/50 dark:placeholder:text-white/50 text-sm text-black dark:text-white resize-none focus:outline-none w-full max-h-24 lg:max-h-36 xl:max-h-48"
+          placeholder="Ask anything..."
+        />
+        <div className="flex flex-row items-center justify-between mt-4">
+          <Optimization />
+          <div className="flex flex-row items-center space-x-2">
+            <div className="flex flex-row items-center space-x-1">
+              <Sources />
+              <ModelSelector />
+              <Attach />
+            </div>
+            <button
+              disabled={message.trim().length === 0}
+              className="bg-sky-500 text-white disabled:text-black/50 dark:disabled:text-white/50 disabled:bg-[#e0e0dc] dark:disabled:bg-[#ececec21] hover:bg-opacity-85 transition duration-100 rounded-full p-2"
+            >
+              <ArrowRight className="bg-background" size={17} />
+            </button>
+          </div>
+        </div>
+      </div>
+    </form>
+  );
+};
+
+export default EmptyChatMessageInput;