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/AGENTS.md

@@ -0,0 +1,57 @@
+# Swift Code Style Guidelines
+
+## Core Style
+
+- **Indentation**: 2 spaces
+- **Braces**: Opening brace on same line
+- **Spacing**: Single space around operators and commas
+- **Naming**: PascalCase for types, camelCase for properties/methods
+
+## File Organization
+
+- Logical directory grouping
+- PascalCase files for types, `+` for extensions
+- Modular design with extensions
+
+## Modern Swift Features
+
+- **@Observable macro**: Replace `ObservableObject`/`@Published`
+- **Swift concurrency**: `async/await`, `Task`, `actor`, `@MainActor`
+- **Result builders**: Declarative APIs
+- **Property wrappers**: Use line breaks for long declarations
+- **Opaque types**: `some` for protocol returns
+
+## Code Structure
+
+- Early returns to reduce nesting
+- Guard statements for optional unwrapping
+- Single responsibility per type/extension
+- Value types over reference types
+
+## Error Handling
+
+- `Result` enum for typed errors
+- `throws`/`try` for propagation
+- Optional chaining with `guard let`/`if let`
+- Typed error definitions
+
+## Architecture
+
+- Protocol-oriented design
+- Dependency injection over singletons
+- Composition over inheritance
+- Factory/Repository patterns
+
+## Debug Assertions
+
+- Use `assert()` for development-time invariant checking
+- Use `assertionFailure()` for unreachable code paths
+- Assertions removed in release builds for performance
+- Precondition checking with `precondition()` for fatal errors
+
+## Memory Management
+
+- `weak` references for cycles
+- `unowned` when guaranteed non-nil
+- Capture lists in closures
+- `deinit` for cleanup