Welcome: Clone Repository quick action

[kirich1409]

Summary

• Adds a third "Clone Repository" Quick Action to the Welcome screen.
• Opens a sheet with URL field + destination folder picker (NSOpenPanel) + Clone/Cancel buttons. Shows a ProgressView while cloning and an Alert on failure.
• Implements GitCloneClient dependency wrapping Process on /usr/bin/git. Task cancellation terminates the subprocess via withTaskCancellationHandler so TCA's .cancel(id:) aborts the clone.
• On success, the cloned folder is added via the existing projectRepository and opened via delegate(.projectSelected(URL)) — no new routing plumbing.
• Auth scope: user's existing git credentials (SSH keys / credential helper). No explicit credential management.

Files

• MacApp/Relay/Welcome/GitCloneClient.swift (new) — dependency + live Process-based clone runner.
• MacApp/Relay/Welcome/CloneRepositorySheet.swift (new) — sheet content view.
• MacApp/Relay/Welcome/WelcomeFeature.swift — adds CloneState sub-state, clone actions, cancellable effect.
• MacApp/Relay/Welcome/WelcomeView.swift — new Clone Repository button (Cmd+Shift+C) + sheet presentation.
• MacApp/RelayTests/WelcomeFeatureTests.swift — 13 new tests for state transitions and effect wiring.

Test plan

• cd MacApp && swiftlint lint --strict — 0 violations.
• xcodebuild build -project MacApp/Relay.xcodeproj -scheme Relay -destination 'platform=macOS,arch=arm64' CODE_SIGN_IDENTITY=- — BUILD SUCCEEDED.
• xcodebuild test ... -only-testing:RelayTests — all 33 unit tests pass (including 13 new clone tests).
• Manual: open app → Welcome → Clone Repository → paste a git URL, pick a folder, clone → app navigates into the cloned project.
• Manual: cancel mid-clone → subprocess terminates, sheet stays open.
• Manual: invalid URL / missing destination → Clone button stays disabled.
• Manual: clone failure (e.g. private repo no keys) → alert shows auth error.

Pre-existing unrelated failures

RelayUITests (7 tests) fail on the local test runner — they are end-to-end UI tests that require a project to be open and are unrelated to this PR (no UI test files were touched).

Closes #149

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Adds a “Clone Repository” quick action to the Welcome screen, wiring a new sheet-driven clone flow into WelcomeFeature using a cancellable Process-based git runner so successful clones are added to the project repository and opened via the existing delegate path.

Changes:

• Introduces GitCloneClient dependency + CloneError for running /usr/bin/git clone with task cancellation support.
• Adds CloneRepositorySheet UI and Welcome screen button/sheet presentation.
• Extends WelcomeFeature with transient clone sub-state/actions and adds unit tests for the new flow.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
MacApp/Relay/Welcome/GitCloneClient.swift	New dependency wrapping git clone via Process, with cancellation support and error classification.
MacApp/Relay/Welcome/CloneRepositorySheet.swift	New SwiftUI sheet for URL/destination inputs, progress display, and error alert.
MacApp/Relay/Welcome/WelcomeFeature.swift	Adds clone sub-state/actions, effect wiring, and cancellation handling.
MacApp/Relay/Welcome/WelcomeView.swift	Adds “Clone Repository…” quick action and presents the clone sheet.
MacApp/RelayTests/WelcomeFeatureTests.swift	Adds coverage for clone sheet state transitions and success/failure paths.

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