feat: Add task naming support for improved debugging

[takeshishimada]

Summary

Implement task naming feature leveraging Swift 6.2's SE-0469 task naming capability. This enhancement allows developers to assign human-readable names to tasks created with .run effects, significantly improving observability during debugging and profiling.

Motivation

Swift 6.2 introduced task naming (SE-0469) to help developers identify tasks in debugging and profiling tools. This PR brings that capability to Flow's .run effects, making it easier to:

• Identify which tasks are running in Xcode debugger
• Track task performance in Instruments
• Understand task behavior with swift-inspect
• Debug complex async workflows

Implementation

Core Changes

1. ActionTask.swift

   • Added optional name: String? parameter to Operation.run case
   • Added name parameter to .run(name:operation:) factory method
   • Ensured name is preserved through all configuration methods (.catch, .cancellable, .priority)

2. TaskManager.swift

   • Added name parameter to executeTask method
   • Passed name to Swift's Task(name:priority:) initializer

3. Store.swift

   • Updated executeRunTask to accept and pass through name parameter
   • Extracted name from ActionTask operation

Tests

Added 6 comprehensive tests covering:

• Basic task naming
• Backward compatibility (name = nil)
• Name preservation through .catch, .cancellable, .priority
• Name preservation through complete configuration chaining

All 299 tests pass (293 existing + 6 new).

Example Usage

// Named task for better debugging
return .run(name: "🔄 Fetch user profile") { state in
    let profile = try await api.fetchProfile()
    state.profile = profile
}

// Dynamic naming with context
return .run(name: "Load user \(userId)") { state in
    let user = try await api.fetchUser(userId)
    state.user = user
}

// Name preserved through method chaining
return .run(name: "Critical operation") { state in
    try await performOperation()
}
.cancellable(id: "op", cancelInFlight: true)
.priority(.high)
.catch { error, state in
    state.error = error
}

Benefits

✅ Improved Debugging: Tasks are easily identifiable in development tools
✅ Better Observability: Human-readable names in profiling and debugging
✅ Backward Compatible: Optional parameter with nil default
✅ Zero Breaking Changes: Existing code works unchanged
✅ Type-Safe: Leverages Swift's native task naming API

Requirements

• Swift 6.2+ (for Task naming API support)

Testing

• ✅ All 299 tests pass
• ✅ Backward compatibility verified
• ✅ Name preservation through chaining verified
• ✅ Build successful with zero warnings

Related

This feature is inspired by similar implementations in other Swift architecture libraries and directly utilizes Swift Evolution proposal SE-0469.

Screenshots

Task names will appear in:

• Xcode debugger's thread list
• Instruments task timeline
• swift-inspect output

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