fix: font loading and chat scrolling issues

- fix: Replace corrupted Merriweather fonts with valid WOFF2 files from @fontsource
- fix: Use CSS @font-face instead of next/font/local for Merriweather (Next.js 16 compatibility)
- fix: Add smart scroll detection to ChatWindow (respects manual scrolling)
- feat: Update app title to "Brachnha Insight"
- feat: Update app description

Co-Authored-By: Claude (glm-4.7) <noreply@anthropic.com>

src/components/features/chat/chat-window.tsx

@@ -1,6 +1,6 @@
 "use client";
 
-import { useEffect, useRef } from 'react';
+import { useEffect, useRef, useState } from 'react';
 import { ChatBubble } from './chat-bubble';
 import { TypingIndicator } from './typing-indicator';
 import { useChatStore } from '@/store/use-chat';
@@ -9,11 +9,39 @@ import { BookOpen, Sparkles } from 'lucide-react';
 export function ChatWindow() {
     const { messages, isTyping } = useChatStore();
     const bottomRef = useRef<HTMLDivElement>(null);
+    const containerRef = useRef<HTMLDivElement>(null);
+    const [isUserScrolling, setIsUserScrolling] = useState(false);
 
-    // Auto-scroll to bottom
+    // Auto-scroll to bottom only when new messages arrive
     useEffect(() => {
-        bottomRef.current?.scrollIntoView({ behavior: 'smooth' });
-    }, [messages, isTyping]);
+        if (!isUserScrolling) {
+            bottomRef.current?.scrollIntoView({ behavior: 'smooth' });
+        }
+    }, [messages.length, isUserScrolling]);
+
+    // Detect when user is manually scrolling
+    useEffect(() => {
+        const container = containerRef.current;
+        if (!container) return;
+
+        const handleScroll = () => {
+            const { scrollTop, scrollHeight, clientHeight } = container;
+            const isAtBottom = scrollHeight - scrollTop - clientHeight < 100;
+
+            // If user scrolls up from bottom, disable auto-scroll
+            if (!isAtBottom && !isUserScrolling) {
+                setIsUserScrolling(true);
+            }
+
+            // If user scrolls back near bottom, re-enable auto-scroll
+            if (isAtBottom && isUserScrolling) {
+                setIsUserScrolling(false);
+            }
+        };
+
+        container.addEventListener('scroll', handleScroll);
+        return () => container.removeEventListener('scroll', handleScroll);
+    }, [isUserScrolling]);
 
     if (!messages || messages.length === 0) {
         return (
@@ -38,7 +66,7 @@ export function ChatWindow() {
     }
 
     return (
-        <div className="h-full flex-1 overflow-y-auto px-4 py-6 scroll-smooth">
+        <div ref={containerRef} className="h-full flex-1 overflow-y-auto px-4 py-6 scroll-smooth">
             <div className="max-w-3xl mx-auto space-y-4">
                 {messages.map((msg) => (
                     <ChatBubble key={msg.id} role={msg.role} content={msg.content} />