feat: adopt new backend api for attachment (#13336)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

* **New Features**
* Introduced a new query for applying document updates using AI,
allowing merged markdown responses.
* Added support for an optional file upload field when creating chat
messages.

* **Improvements**
* Enhanced recent Copilot sessions query with pagination by adding an
offset parameter.
* Refined attachment handling in chat responses to better distinguish
between single and multiple file uploads, improving reliability.

* **Bug Fixes**
  * Minor update to error handling for clearer messaging.

* **Chores**
* Cleaned up and updated iOS project configuration files for improved
build consistency.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/frontend/apps/ios/App/Packages/AffineGraphQL/Sources/Schema/InputObjects/CreateChatMessageInput.graphql.swift

@@ -12,6 +12,7 @@ public struct CreateChatMessageInput: InputObject {
 
   public init(
     attachments: GraphQLNullable<[String]> = nil,
+    blob: GraphQLNullable<Upload> = nil,
     blobs: GraphQLNullable<[Upload]> = nil,
     content: GraphQLNullable<String> = nil,
     params: GraphQLNullable<JSON> = nil,
@@ -19,6 +20,7 @@ public struct CreateChatMessageInput: InputObject {
   ) {
     __data = InputDict([
       "attachments": attachments,
+      "blob": blob,
       "blobs": blobs,
       "content": content,
       "params": params,
@@ -31,6 +33,11 @@ public struct CreateChatMessageInput: InputObject {
     set { __data["attachments"] = newValue }
   }
 
+  public var blob: GraphQLNullable<Upload> {
+    get { __data["blob"] }
+    set { __data["blob"] = newValue }
+  }
+
   public var blobs: GraphQLNullable<[Upload]> {
     get { __data["blobs"] }
     set { __data["blobs"] = newValue }