Bump Tuist to 4.206.0

[Kyle-Ye]

Current version

4.203.4

Target version

4.206.0

Upstream release or pull request

tuist/tuist#12411

Upgrade motivation

• Fixes Tuist-generated projects defining SWIFT_PACKAGE=1 without generating and injecting the SwiftPM Objective-C resource bundle accessor for local package targets with resources.
• Fixes duplicated unconditional OTHER_SWIFT_FLAGS when shared Swift settings are combined with an SDK-conditioned setting. With Xcode 26.6, the duplicated flags repeat availability macro definitions and break the macOS UI test build.
• Adopts the fix from tuist/tuist#12411, which generates Objective-C accessors for local Swift packages and corrects conditional package build-setting mapping.
• Allows affected OpenSwiftUI Objective-C targets to use SWIFTPM_MODULE_BUNDLE without a Tuist-specific preprocessor fallback.

Expected compatibility and migration impact

No manifest migration is expected. Generated projects for affected Objective-C package targets will gain the SwiftPM-compatible resource bundle accessor and injected header. Unconditional package settings will no longer be copied into platform-specific variants, so generated OTHER_SWIFT_FLAGS should contain each shared setting only once.

Acceptance criteria

• Both Tuist pins use 4.206.0.
• Default and Compute Example projects generate and remain buildable.
• Affected Objective-C package targets receive the SwiftPM-compatible resource bundle accessor.
• Generated iOS and macOS compiler commands contain each shared Swift flag and availability macro definition once.
• -index-ignore-system-modules can return to a macOS-only condition without duplicating OTHER_SWIFT_FLAGS.
• Version-specific workarounds are removed or documented.

Additional context

The upstream fix was verified with Tuist 4.206.0-canary.16 against OpenSwiftUI generated projects, including the Objective-C accessor and OTHER_SWIFT_FLAGS cases. The fix merged before the 4.206.0 canary series, so the stable 4.206.0 target will include it once released.

Related upstream issues:

• Generated projects define SWIFT_PACKAGE without providing the Objective-C resource bundle accessor tuist/tuist#12375
• Platform-conditioned SwiftPM settings duplicate unconditional OTHER_SWIFT_FLAGS tuist/tuist#12377