feat: add Zero queries for all 6 synced tables

Define named queries matching each Electric hook's data needs:
- notifications.byUser (use-inbox)
- documents.bySpace (use-documents, use-documents-processing)
- connectors.bySpace (use-connectors-electric)
- messages.byThread (use-messages-electric)
- comments.byThread (use-comments-electric)
- chatSession.byThread (use-chat-session-state)

Also moves schema files from zero/tables/ to zero/schema/ for
consistent modular folder structure.

surfsense_web/zero/queries/documents.ts

@@ -0,0 +1,21 @@
+import { defineQuery } from "@rocicorp/zero";
+import { z } from "zod";
+import { zql } from "../schema/index";
+
+export const documentQueries = {
+	bySpace: defineQuery(
+		z.object({ searchSpaceId: z.number() }),
+		({ args: { searchSpaceId } }) =>
+			zql.documents.where("searchSpaceId", searchSpaceId).orderBy("createdAt", "desc"),
+	),
+};
+
+export const connectorQueries = {
+	bySpace: defineQuery(
+		z.object({ searchSpaceId: z.number() }),
+		({ args: { searchSpaceId } }) =>
+			zql.search_source_connectors
+				.where("searchSpaceId", searchSpaceId)
+				.orderBy("createdAt", "desc"),
+	),
+};