chore: fix building the app (#13606)

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

- New Features
  - Built-in Then-style DSL for fluent configuration.
- Centralized theming via a new resources library exposing standardized
colors and icons for SwiftUI and UIKit.

- Refactor
  - Migrated color and icon accessors to the new resources provider.
  - Removed redundant imports and streamlined UI configuration.

- Dependencies
  - Updated MarkdownView to 3.4.2.
- Removed the Then third-party dependency; updated package sources;
added resources package and assets.

- Documentation
  - Added iOS Swift code style and architecture guidelines.

- Chores
  - Updated Xcode project format and repository ignore rules.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/frontend/apps/ios/App/App.xcworkspace/xcshareddata/swiftpm/Package.resolved

@@ -41,8 +41,8 @@
       "kind" : "remoteSourceControl",
       "location" : "https://github.com/Lakr233/MarkdownView",
       "state" : {
-        "revision" : "1b0267f115274260d7cc875c4e9043f976f003a2",
-        "version" : "3.4.1"
+        "revision" : "c052f57768436212c91e4369d76181c38eaa3ba3",
+        "version" : "3.4.2"
       }
     },
     {
@@ -107,15 +107,6 @@
         "revision" : "cfd646dcac0c5553e21ebf1ee05f9078277518bc",
         "version" : "1.7.2"
       }
-    },
-    {
-      "identity" : "then",
-      "kind" : "remoteSourceControl",
-      "location" : "https://github.com/devxoul/Then",
-      "state" : {
-        "revision" : "d41ef523faef0f911369f79c0b96815d9dbb6d7a",
-        "version" : "3.0.0"
-      }
     }
   ],
   "version" : 2