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/schema/index.ts

@@ -0,0 +1,41 @@
+import { createSchema, createBuilder, relationships } from "@rocicorp/zero";
+import { chatCommentTable, chatSessionStateTable, newChatMessageTable } from "./chat";
+import { documentTable, searchSourceConnectorTable } from "./documents";
+import { notificationTable } from "./inbox";
+
+const chatCommentRelationships = relationships(chatCommentTable, ({ one }) => ({
+	message: one({
+		sourceField: ["messageId"],
+		destSchema: newChatMessageTable,
+		destField: ["id"],
+	}),
+	parent: one({
+		sourceField: ["parentId"],
+		destSchema: chatCommentTable,
+		destField: ["id"],
+	}),
+}));
+
+const newChatMessageRelationships = relationships(newChatMessageTable, ({ many }) => ({
+	comments: many({
+		sourceField: ["id"],
+		destSchema: chatCommentTable,
+		destField: ["messageId"],
+	}),
+}));
+
+export const schema = createSchema({
+	tables: [
+		notificationTable,
+		documentTable,
+		searchSourceConnectorTable,
+		newChatMessageTable,
+		chatCommentTable,
+		chatSessionStateTable,
+	],
+	relationships: [chatCommentRelationships, newChatMessageRelationships],
+});
+
+export type Schema = typeof schema;
+
+export const zql = createBuilder(schema);