fix: resolve runtime crashes in tool-ui components and backend import errors

Backend:
- Remove dead imports (display_image, link_preview, knowledge_base) from tools registry and __init__
- Delete orphaned elif chain (lines 784-1046) in knowledge_base.py left after asyncio.gather refactor
- Add missing NotionAPIError class to notion_history.py

Frontend:
- Add display-image.tsx, link-preview.tsx, scrape-webpage.tsx tool UI components
- Fix GeneratePodcastToolUI: add null guard for no-props render + optional chaining on status/args
- Fix SaveMemoryToolUI/RecallMemoryToolUI: add null guard when rendered without props in provider
- Update launch.json to use pnpm on port 3999

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

surfsense_web/components/tool-ui/display-image.tsx

@@ -0,0 +1,54 @@
+"use client";
+
+import { makeAssistantToolUI } from "@assistant-ui/react";
+import { z } from "zod";
+import { ImageIcon } from "lucide-react";
+
+const DisplayImageArgsSchema = z.object({
+	url: z.string().optional(),
+	alt: z.string().optional(),
+	caption: z.string().optional(),
+});
+
+const DisplayImageResultSchema = z.object({
+	url: z.string().optional(),
+	alt: z.string().optional(),
+	caption: z.string().optional(),
+}).passthrough();
+
+type DisplayImageArgs = z.infer<typeof DisplayImageArgsSchema>;
+type DisplayImageResult = z.infer<typeof DisplayImageResultSchema>;
+
+export const DisplayImageToolUI = makeAssistantToolUI<DisplayImageArgs, DisplayImageResult>({
+	toolName: "display_image",
+	render: ({ args, result, status }) => {
+		const isLoading = status.type === "running";
+		const imageUrl = result?.url ?? args?.url;
+		const altText = result?.alt ?? args?.alt ?? "Image";
+		const caption = result?.caption ?? args?.caption;
+
+		if (isLoading) {
+			return (
+				<div className="my-3 flex items-center gap-2 rounded-lg border bg-card/60 px-4 py-3">
+					<ImageIcon className="size-4 animate-pulse text-muted-foreground" />
+					<span className="text-sm text-muted-foreground">Loading image...</span>
+				</div>
+			);
+		}
+
+		if (!imageUrl) return null;
+
+		return (
+			<div className="my-3 rounded-lg border bg-card/60 overflow-hidden">
+				<img
+					src={imageUrl}
+					alt={altText}
+					className="w-full max-h-96 object-contain"
+				/>
+				{caption && (
+					<p className="px-4 py-2 text-sm text-muted-foreground">{caption}</p>
+				)}
+			</div>
+		);
+	},
+});