fix: offline intitalization using cached config

[jonathannorris]

Improve Client Build Process Resilience and Cache Handling

Summary

Enhances the DevCycle iOS Client SDK to gracefully handle network failures during initialization by leveraging cached configurations, while maintaining appropriate error handling for user operations.

Key Changes

🔧 Client Build Process (setup)

• ✅ No longer throws errors when network fails but cached config is available
• ✅ Falls back to cached configuration for offline resilience
• ❌ Only returns errors when both network fails AND no cache exists

👤 User Operations

• identifyUser: Uses cached config fallback, only errors if no cache available
• resetUser: Always returns errors on network failure (requires fresh anonymous user)

🧹 Code Cleanup

• Removed unused Cache struct and load() method (~50 lines of dead code)
• Simplified cache service protocol and implementations
• Combined redundant config checks and improved code flow

🧪 Enhanced Testing

• Added comprehensive test coverage for offline scenarios
• Tests verify cache fallback behavior vs. error-first behavior
• Validates client state protection during failures

Behavior Matrix

Scenario	Build	identifyUser	resetUser
Network success	✅	✅	✅
Network fails + Cache	✅	✅	❌
Network fails + No cache	❌	❌	❌

This ensures the SDK works reliably in offline scenarios while maintaining clear error boundaries for operations that require fresh data.

[Copilot]

Pull Request Overview

This PR improves offline resiliency for the DevCycle iOS Client SDK by leveraging cached configurations when network operations fail. Key changes include fallback to cached configuration in the build process, refined error propagation for user operations, and enhanced test coverage for offline scenarios.

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
DevCycleTests/Networking/DevCycleServiceTests.swift	Removed unused cache load function in the mock cache service.
DevCycleTests/Models/DevCycleClientTests.swift	Added and modified tests to verify cached config behavior.
DevCycle/Models/Cache.swift	Removed the legacy Cache struct and cleaned up cache methods.
DevCycle/DevCycleClient.swift	Updated error handling and cache usage during setup, identifyUser, and resetUser operations.