Add Foundation ProtobufMessage conformances (URL, UUID, Data, Locale)

[Kyle-Ye]

Summary

• Add ProtobufMessage conformances for URL, UUID, Data, and Locale in a single file Foundation+ProtobufMessage.swift
• Add C stubs and dual test file to verify encoding/decoding matches SwiftUICore's implementation
• Reverse engineered from SwiftUICore iOS 18.5 Simulator binary via Hopper

Test plan

• swift test --filter FoundationProtobufMessage passes all 4 test suites (URL, UUID, Data, Locale)
• Run dual tests on device to verify SwiftUI symbol compatibility

[augmentcode]

🤖 Augment PR Summary

Summary: This PR adds protobuf serialization support for several Foundation types to better match SwiftUICore’s on-device encoding/decoding.

Changes:

• Added `ProtobufMessage` conformances for URL, UUID, Data (WIP), and Locale in Foundation+ProtobufMessage.swift.
• Introduced SymbolLocator-based C stubs to call SwiftUICore’s implementations for dual-compat testing.
• Added dual tests that verify OpenSwiftUICore and SwiftUICore produce identical protobuf bytes and decode to identical values (guarded by canImport(SwiftUI, _underlyingVersion: 6.5.4)).
• Updated the Example app view and adjusted example/package dependency resolution files.
• Changed the package manifest to default USE_LOCAL_DEPS to enabled.

Technical Notes: URL encoding includes an optional nested base URL message; UUID uses a 16-byte data payload; tests assert exact hex encodings to ensure wire-format parity with SwiftUICore.

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[augmentcode]

Review completed. 1 suggestions posted.

Comment augment review to trigger a new review at any time.

[augmentcode]

Defaulting USE_LOCAL_DEPS to true means a default swift build will try to resolve sibling path dependencies (e.g. ../OpenCoreGraphics, ../OpenObservation) and can fail for users/CI that don’t have those checkouts. Is it intentional that the “local deps” mode is now the default behavior?

Severity: high

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