chore: define view model (#12949)

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

## Summary by CodeRabbit

* **New Features**
* Introduced a chat interface with message list, empty state view, and
support for user, assistant, and system messages.
* Added a chat manager for session and message handling, including
session creation, message sending, and error management.
* Implemented various chat cell types (attachments, context references,
workflow status, loading, and error cells) with corresponding data
models and view models.
* Enabled asynchronous message sending from the input box with error
alerts and automatic session creation.
* Added workflow and context-related models for advanced chat features.

* **Enhancements**
* Improved UI responsiveness with table view updates and dynamic empty
state handling.
  * Provided a method to clear all attachments in the input box.

* **Bug Fixes / Style**
* Refined code formatting, access control, and minor stylistic
improvements across multiple files for consistency.

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

packages/frontend/apps/ios/App/App/JSValueContainerExt.swift

@@ -10,44 +10,44 @@ enum RequestParamError: Error {
   case request(key: String)
 }
 
-extension JSValueContainer {
-  public func getStringEnsure(_ key: String) throws -> String {
-    guard let str = self.getString(key) else {
+public extension JSValueContainer {
+  func getStringEnsure(_ key: String) throws -> String {
+    guard let str = getString(key) else {
       throw RequestParamError.request(key: key)
     }
     return str
   }
-  
-  public func getIntEnsure(_ key: String) throws -> Int {
-    guard let int = self.getInt(key) else {
+
+  func getIntEnsure(_ key: String) throws -> Int {
+    guard let int = getInt(key) else {
       throw RequestParamError.request(key: key)
     }
     return int
   }
-  
-  public func getDoubleEnsure(_ key: String) throws -> Double {
-    guard let doub = self.getDouble(key) else {
+
+  func getDoubleEnsure(_ key: String) throws -> Double {
+    guard let doub = getDouble(key) else {
       throw RequestParamError.request(key: key)
     }
     return doub
   }
-  
-  public func getBoolEnsure(_ key: String) throws -> Bool {
-    guard let bool = self.getBool(key) else {
+
+  func getBoolEnsure(_ key: String) throws -> Bool {
+    guard let bool = getBool(key) else {
       throw RequestParamError.request(key: key)
     }
     return bool
   }
-  
-  public func getArrayEnsure(_ key: String) throws -> JSArray {
-    guard let arr = self.getArray(key) else {
+
+  func getArrayEnsure(_ key: String) throws -> JSArray {
+    guard let arr = getArray(key) else {
       throw RequestParamError.request(key: key)
     }
     return arr
   }
-  
-  public func getArrayEnsure<T>(_ key: String, _ ofType: T.Type) throws -> [T] {
-    guard let arr = self.getArray(key, ofType) else {
+
+  func getArrayEnsure<T>(_ key: String, _ ofType: T.Type) throws -> [T] {
+    guard let arr = getArray(key, ofType) else {
       throw RequestParamError.request(key: key)
     }
     return arr