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/Intelligents/Sources/Intelligents/ChatManager/ChatManager+Stream.swift

@@ -167,8 +167,12 @@ private extension ChatManager {
       "files": [String](), // attachment in context, keep nil for now
       "searchMode": editorData.isSearchEnabled ? "MUST" : "AUTO",
     ]
-    let attachmentFieldName = "options.blobs"
-    var uploadableAttachments: [GraphQLFile] = [
+    let hasMultipleAttachmentBlobs = [
+      editorData.fileAttachments.count,
+      editorData.documentAttachments.count,
+    ].reduce(0, +) > 1
+    let attachmentFieldName = hasMultipleAttachmentBlobs ? "options.blobs" : "options.blob"
+    let uploadableAttachments: [GraphQLFile] = [
       editorData.fileAttachments.map { file -> GraphQLFile in
         .init(fieldName: attachmentFieldName, originalName: file.name, data: file.data ?? .init())
       },
@@ -177,15 +181,10 @@ private extension ChatManager {
       },
     ].flatMap(\.self)
     assert(uploadableAttachments.allSatisfy { !($0.data?.isEmpty ?? true) })
-    // in Apollo, filed name is handled as attached object to field when there is only one attachment
-    // to use array on our server, we need to append a dummy attachment
-    // which is ignored if data is empty and name is empty
-    if uploadableAttachments.count == 1 {
-      uploadableAttachments.append(.init(fieldName: attachmentFieldName, originalName: "", data: .init()))
-    }
     guard let input = try? CreateChatMessageInput(
       attachments: [],
-      blobs: .some([]), // must have the placeholder
+      blob: hasMultipleAttachmentBlobs ? .none : "",
+      blobs: hasMultipleAttachmentBlobs ? .some([]) : .none,
       content: .some(contextSnippet.isEmpty ? editorData.text : "\(contextSnippet)\n\(editorData.text)"),
       params: .some(AffineGraphQL.JSON(_jsonValue: messageParameters)),
       sessionId: sessionId

packages/frontend/apps/ios/App/Packages/Intelligents/Sources/Intelligents/IntelligentContext/IntelligentContext.swift

@@ -62,7 +62,7 @@ public class IntelligentContext {
         "Login required: \(reason)"
       case let .sessionCreationFailed(reason):
         "Session creation failed: \(reason)"
-      case let .featureClosed:
+      case .featureClosed:
         "Intelligent feature closed"
       }
     }