Initial commit: EGBE chatbot template

Stripped from vercel/chatbot (Apache 2.0):
- Dropped @vercel/* packages and AI Gateway
- Removed artifacts feature (code/text/sheet/image side panel)
- Switched AI provider to @ai-sdk/openai-compatible -> EGBE LiteLLM
- Replaced Vercel Blob upload with data URLs
- Dropped Redis resumable streams and rate limiter (in-memory now)
- Added Dockerfile (Next.js standalone) + entrypoint that runs migrations
- Wired DATABASE_URL, EGBE_AI_API_URL/KEY, NEXT_PUBLIC_BASE_URL for app-deploy.sh

hooks/use-scroll-to-bottom.tsx

@@ -0,0 +1,124 @@
+import { useCallback, useEffect, useRef, useState } from "react";
+
+export function useScrollToBottom() {
+  const containerRef = useRef<HTMLDivElement>(null);
+  const endRef = useRef<HTMLDivElement>(null);
+  const [isAtBottom, setIsAtBottom] = useState(true);
+  const isAtBottomRef = useRef(true);
+  const isUserScrollingRef = useRef(false);
+
+  useEffect(() => {
+    isAtBottomRef.current = isAtBottom;
+  }, [isAtBottom]);
+
+  const checkIfAtBottom = useCallback(() => {
+    if (!containerRef.current) {
+      return true;
+    }
+    const { scrollTop, scrollHeight, clientHeight } = containerRef.current;
+    return scrollTop + clientHeight >= scrollHeight - 100;
+  }, []);
+
+  const scrollToBottom = useCallback((behavior: ScrollBehavior = "smooth") => {
+    if (!containerRef.current) {
+      return;
+    }
+    containerRef.current.scrollTo({
+      top: containerRef.current.scrollHeight,
+      behavior,
+    });
+  }, []);
+
+  useEffect(() => {
+    const container = containerRef.current;
+    if (!container) {
+      return;
+    }
+
+    let scrollTimeout: ReturnType<typeof setTimeout>;
+
+    const handleScroll = () => {
+      isUserScrollingRef.current = true;
+      clearTimeout(scrollTimeout);
+
+      const atBottom = checkIfAtBottom();
+      setIsAtBottom(atBottom);
+      isAtBottomRef.current = atBottom;
+
+      scrollTimeout = setTimeout(() => {
+        isUserScrollingRef.current = false;
+      }, 150);
+    };
+
+    container.addEventListener("scroll", handleScroll, { passive: true });
+    return () => {
+      container.removeEventListener("scroll", handleScroll);
+      clearTimeout(scrollTimeout);
+    };
+  }, [checkIfAtBottom]);
+
+  useEffect(() => {
+    const container = containerRef.current;
+    if (!container) {
+      return;
+    }
+
+    const scrollIfNeeded = () => {
+      if (isAtBottomRef.current && !isUserScrollingRef.current) {
+        requestAnimationFrame(() => {
+          container.scrollTo({
+            top: container.scrollHeight,
+            behavior: "instant",
+          });
+          setIsAtBottom(true);
+          isAtBottomRef.current = true;
+        });
+      }
+    };
+
+    const mutationObserver = new MutationObserver(scrollIfNeeded);
+    mutationObserver.observe(container, {
+      childList: true,
+      subtree: true,
+      characterData: true,
+    });
+
+    const resizeObserver = new ResizeObserver(scrollIfNeeded);
+    resizeObserver.observe(container);
+
+    for (const child of container.children) {
+      resizeObserver.observe(child);
+    }
+
+    return () => {
+      mutationObserver.disconnect();
+      resizeObserver.disconnect();
+    };
+  }, []);
+
+  function onViewportEnter() {
+    setIsAtBottom(true);
+    isAtBottomRef.current = true;
+  }
+
+  function onViewportLeave() {
+    setIsAtBottom(false);
+    isAtBottomRef.current = false;
+  }
+
+  const reset = useCallback(() => {
+    setIsAtBottom(true);
+    isAtBottomRef.current = true;
+    isUserScrollingRef.current = false;
+  }, []);
+
+  return {
+    containerRef,
+    endRef,
+    isAtBottom,
+    scrollToBottom,
+    onViewportEnter,
+    onViewportLeave,
+    reset,
+  };
+}