Recover canonical Objective-C protocol conformances

[lynnswap]

Purpose

Restore direct Objective-C protocol conformances when dyld canonical protocol objects live in cache-wide storage outside every Mach-O image.

Closes #60.

Changes

• Pin MachOObjCSection to c7716997aa1ace417c43fcd15b5322dbbe79ec54, which mirrors objc4's canonical and name-remap paths while validating active shared-cache provenance, runtime preoptimization state, mapping boundaries, mandatory layout size, and bounded cumulative name reads.
• Pin MachOSwiftSection to the coherent cohort commit 122f50ee5196816a0d9d628a56a978636bc9bb03 so its transitive MachOObjCSection dependency matches the direct pin.
• Update Package.resolved and the exact dependency-pin contract test.

Testing

• swift test
• scripts/test-release-scripts.sh
• iOS Core/CoreTests compile checks
• watchOS Core/CoreTests/simulator-helper compile checks
• MachOObjCSection: 54 protocol safety tests, 9 relative-member safety tests, release build, iOS Simulator arm64/x86_64, watchOS Simulator arm64, and watchOS device arm64_32 builds
• MachOSwiftSection: coherent remote graph and 640 non-baseline tests
• iOS 27.0 beta 24A5390f ARKit smoke: ARAnchor renders <ARDaemonSecureCoding, ARAnchorCopying, NSSecureCoding> with zero ARKit Objective-C metadata warnings
• watchOS 27.0 beta 24R5325f AVFAudio smoke: AVAudioBuffer renders <NSCopying, NSMutableCopying> and AVAudioFormat renders <NSSecureCoding> with zero AVFAudio Objective-C metadata warnings
• Final branch-wide Codex review: no actionable findings