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/index.ts

@@ -0,0 +1,13 @@
+import { defineQueries } from "@rocicorp/zero";
+import { chatSessionQueries, commentQueries, messageQueries } from "./chat";
+import { connectorQueries, documentQueries } from "./documents";
+import { notificationQueries } from "./inbox";
+
+export const queries = defineQueries({
+	notifications: notificationQueries,
+	documents: documentQueries,
+	connectors: connectorQueries,
+	messages: messageQueries,
+	comments: commentQueries,
+	chatSession: chatSessionQueries,
+});