feat(protect): add support for deeply nested protect schemas

.changeset/smart-worlds-wait.md

@@ -0,0 +1,5 @@
+---
+"@cipherstash/protect": minor
+---
+
+Added support for deeply nested protect schemas to support more complex model objects.

docs/reference/schema.md

@@ -8,6 +8,7 @@ Protect.js lets you define a schema in TypeScript with properties that map to yo
 - [Understanding schema files](#understanding-schema-files)
 - [Defining your schema](#defining-your-schema)
   - [Searchable encryption](#searchable-encryption)
+  - [Nested objects](#nested-objects)
 - [Available index options](#available-index-options)
 - [Initializing the Protect client](#initializing-the-protect-client)
 
@@ -75,6 +76,45 @@ export const protectedUsers = csTable("users", {
 });
 ```
 
+### Nested objects
+
+Protect.js supports nested objects in your schema, allowing you to encrypt **but not search on** nested properties. You can define nested objects up to 3 levels deep.
+This is useful for data stores that have less structured data, like NoSQL databases.
+
+You can define nested objects by using the `csValue` function to define a value in a nested object. The value naming convention of the `csValue` function is a dot-separated string of the nested object path, e.g. `profile.name` or `profile.address.street`.
+
+> [!NOTE]
+> Using nested objects is not recommended for SQL databases, as it will not be searchable.
+> You should either use a JSON data type and encrypt the entire object, or use a separate column for each nested property.
+
+```ts
+import { csTable, csColumn, csValue } from "@cipherstash/protect";
+
+export const protectedUsers = csTable("users", {
+  email: csColumn("email").freeTextSearch().equality().orderAndRange(),
+  profile: {
+    name: csValue("profile.name"),
+    address: {
+      street: csValue("profile.address.street"),
+      location: {
+        coordinates: csValue("profile.address.location.coordinates"),
+      },
+    },
+  },
+});
+```
+
+When working with nested objects:
+- Searchable encryption is not supported on nested objects
+- Each level can have its own encrypted fields
+- The maximum nesting depth is 3 levels
+- Null and undefined values are supported at any level
+- Optional nested objects are supported
+
+> [!WARNING]
+> TODO: The schema builder does not validate the values you supply to the `csValue` or `csColumn` functions.
+> These values are meant to be unique, and and cause unexpected behavior if they are not defined correctly.
+
 ## Available index options
 
 The following index options are available for your schema: