refactor: replace document type counts atom with real-time hook

- Removed the `documentTypeCountsAtom` and its associated logic from the document query atoms.
- Introduced `useZeroDocumentTypeCounts` hook to provide real-time document type counts, enhancing responsiveness as documents are indexed.
- Updated components to utilize the new hook for fetching document type counts, ensuring instant updates in the UI.

surfsense_web/hooks/use-zero-document-type-counts.ts

@@ -0,0 +1,31 @@
+"use client";
+
+import { useQuery } from "@rocicorp/zero/react";
+import { useMemo } from "react";
+import { queries } from "@/zero/queries";
+
+/**
+ * Real-time document type counts derived from Zero's live document sync.
+ * Updates instantly as documents are created, deleted, or change type.
+ */
+export function useZeroDocumentTypeCounts(
+	searchSpaceId: number | string | null
+): Record<string, number> | undefined {
+	const numericId = searchSpaceId != null ? Number(searchSpaceId) : null;
+
+	const [zeroDocuments] = useQuery(
+		queries.documents.bySpace({ searchSpaceId: numericId ?? -1 })
+	);
+
+	return useMemo(() => {
+		if (!zeroDocuments || numericId == null) return undefined;
+
+		const counts: Record<string, number> = {};
+		for (const doc of zeroDocuments) {
+			if (doc.id != null && doc.title != null && doc.title !== "") {
+				counts[doc.documentType] = (counts[doc.documentType] || 0) + 1;
+			}
+		}
+		return counts;
+	}, [zeroDocuments, numericId]);
+}