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

components/chat/preview-attachment.tsx

@@ -0,0 +1,54 @@
+import type { Attachment } from "@/lib/types";
+import { Spinner } from "../ui/spinner";
+import { CrossSmallIcon } from "./icons";
+
+export const PreviewAttachment = ({
+  attachment,
+  isUploading = false,
+  onRemove,
+}: {
+  attachment: Attachment;
+  isUploading?: boolean;
+  onRemove?: () => void;
+}) => {
+  const { name, url, contentType } = attachment;
+
+  return (
+    <div
+      className="group relative h-24 w-24 shrink-0 overflow-hidden rounded-xl border border-border/40 bg-muted"
+      data-testid="input-attachment-preview"
+    >
+      {contentType?.startsWith("image") ? (
+        // eslint-disable-next-line @next/next/no-img-element
+        <img
+          alt={name ?? "attachment"}
+          className="size-full object-cover"
+          src={url}
+        />
+      ) : (
+        <div className="flex size-full items-center justify-center text-muted-foreground text-xs">
+          File
+        </div>
+      )}
+
+      {isUploading && (
+        <div
+          className="absolute inset-0 flex items-center justify-center rounded-xl bg-black/40 backdrop-blur-sm"
+          data-testid="input-attachment-loader"
+        >
+          <Spinner className="size-5" />
+        </div>
+      )}
+
+      {onRemove && !isUploading && (
+        <button
+          className="absolute top-1.5 right-1.5 flex size-5 items-center justify-center rounded-full bg-black/60 text-white opacity-0 backdrop-blur-sm transition-opacity hover:bg-black/80 group-hover:opacity-100"
+          onClick={onRemove}
+          type="button"
+        >
+          <CrossSmallIcon size={10} />
+        </button>
+      )}
+    </div>
+  );
+};