feat: add Zero schema with 6 table definitions and relationships

- Create zero/tables/inbox.ts (notifications)
- Create zero/tables/documents.ts (documents, search_source_connectors)
- Create zero/tables/chat.ts (new_chat_messages, chat_comments, chat_session_state)
- Create zero/schema.ts (combines tables, defines relationships, exports zql)
- Consolidate Zero type augmentations into types/zero.d.ts

surfsense_web/zero/tables/inbox.ts

@@ -0,0 +1,16 @@
+import { table, string, number, boolean, json } from "@rocicorp/zero";
+
+export const notificationTable = table("notifications")
+	.columns({
+		id: number(),
+		userId: string().from("user_id"),
+		searchSpaceId: number().optional().from("search_space_id"),
+		type: string(),
+		title: string(),
+		message: string(),
+		read: boolean(),
+		metadata: json().optional(),
+		createdAt: number().from("created_at"),
+		updatedAt: number().optional().from("updated_at"),
+	})
+	.primaryKey("id");