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/Chat.tsx

@@ -0,0 +1,108 @@
+'use client';
+
+import { Fragment, useEffect, useRef, useState } from 'react';
+import MessageInput from './MessageInput';
+import MessageBox from './MessageBox';
+import MessageBoxLoading from './MessageBoxLoading';
+import { useChat } from '@/lib/hooks/useChat';
+
+const Chat = () => {
+  const { sections, loading, messageAppeared, messages } = useChat();
+
+  const [dividerWidth, setDividerWidth] = useState(0);
+  const dividerRef = useRef<HTMLDivElement | null>(null);
+  const messageEnd = useRef<HTMLDivElement | null>(null);
+  const lastScrolledRef = useRef<number>(0);
+
+  useEffect(() => {
+    const updateDividerWidth = () => {
+      if (dividerRef.current) {
+        setDividerWidth(dividerRef.current.offsetWidth);
+      }
+    };
+
+    updateDividerWidth();
+
+    const resizeObserver = new ResizeObserver(() => {
+      updateDividerWidth();
+    });
+
+    const currentRef = dividerRef.current;
+    if (currentRef) {
+      resizeObserver.observe(currentRef);
+    }
+
+    window.addEventListener('resize', updateDividerWidth);
+
+    return () => {
+      if (currentRef) {
+        resizeObserver.unobserve(currentRef);
+      }
+      resizeObserver.disconnect();
+      window.removeEventListener('resize', updateDividerWidth);
+    };
+  }, [sections.length]);
+
+  useEffect(() => {
+    const scroll = () => {
+      messageEnd.current?.scrollIntoView({ behavior: 'auto' });
+    };
+
+    if (messages.length === 1) {
+      document.title = `${messages[0].query.substring(0, 30)} - GooSeek`;
+    }
+
+    if (sections.length > lastScrolledRef.current) {
+      scroll();
+      lastScrolledRef.current = sections.length;
+    }
+  }, [messages]);
+
+  return (
+    <div className="flex flex-col space-y-6 pt-8 pb-44 lg:pb-28 sm:mx-4 md:mx-8">
+      {sections.map((section, i) => {
+        const isLast = i === sections.length - 1;
+
+        return (
+          <Fragment key={section.message.messageId}>
+            <MessageBox
+              section={section}
+              sectionIndex={i}
+              dividerRef={isLast ? dividerRef : undefined}
+              isLast={isLast}
+            />
+            {!isLast && (
+              <div className="h-px w-full bg-light-secondary dark:bg-dark-secondary" />
+            )}
+          </Fragment>
+        );
+      })}
+      {loading && !messageAppeared && <MessageBoxLoading />}
+      <div ref={messageEnd} className="h-0" />
+      {dividerWidth > 0 && (
+        <div
+          className="fixed z-40 bottom-24 lg:bottom-6"
+          style={{ width: dividerWidth }}
+        >
+          <div
+            className="pointer-events-none absolute -bottom-6 left-0 right-0 h-[calc(100%+24px+24px)] dark:hidden"
+            style={{
+              background:
+                'linear-gradient(to top, #ffffff 0%, #ffffff 35%, rgba(255,255,255,0.95) 45%, rgba(255,255,255,0.85) 55%, rgba(255,255,255,0.7) 65%, rgba(255,255,255,0.5) 75%, rgba(255,255,255,0.3) 85%, rgba(255,255,255,0.1) 92%, transparent 100%)',
+            }}
+          />
+          <div
+            className="pointer-events-none absolute -bottom-6 left-0 right-0 h-[calc(100%+24px+24px)] hidden dark:block"
+            style={{
+              background:
+                'linear-gradient(to top, #0d1117 0%, #0d1117 35%, rgba(13,17,23,0.95) 45%, rgba(13,17,23,0.85) 55%, rgba(13,17,23,0.7) 65%, rgba(13,17,23,0.5) 75%, rgba(13,17,23,0.3) 85%, rgba(13,17,23,0.1) 92%, transparent 100%)',
+            }}
+          />
+          <MessageInput />
+        </div>
+      )}
+    </div>
+  );
+};
+
+export default Chat;