feat: add macless iPhone build pipeline

[ShiroKSH]

Summary

• Integrate Goal 3 with the current Developer Experience baseline while preserving the local iOS device, deployment, IDE, asset, release, and VS Code surfaces.
• Add the versioned remote-build protocol, GitHub Actions provider, pinned macOS worker, deterministic source/archive transport, strict client-side artifact validation, cancellation and cleanup, and manual Apple Development signing setup.
• Add the reproducible Goal 3 integration package and final evidence/status documentation.

Validation

• CI run 31258657173: all five required jobs passed on Linux, Rust 1.92, Ubuntu, macOS, and Windows.
• Final branch CI run 31259704034 attempt 2: all five required jobs passed; the rerun recovered a transient macOS runner I/O failure.
• Pull request CI run 31259834091: Linux quality/docs, Rust 1.92, Ubuntu, macOS, and Windows all passed.
• CodeQL run 31259833087, VS Code extension run 31259834084, and platform-artifact run 31259834079 passed.
• Linux acceptance run 31258657179 and macOS worker run 31258758075: exact-revision GitHub dispatch, real unsigned aarch64-apple-ios compile, sealed archive upload/download, independent client verification, and cleanup passed.
• Acceptance artifact 9022219517: 46,848,377 bytes; API digest 071a321305f361a3107128bf992322de77fa12114f6ef4b36a1972b2f3e7442c; inner archive SHA-256 ebe4c99b0bab31f63b41fa043cf74a0ae3b2663faf0cef9bc0feeb2d5bc4aa28.
• Integration package: 42/42 checksums, bundle verification, commit/file manifests, 33-patch replay, aggregate-patch replay, and integrated ancestry/tree checks passed. Package ID: f7bd895d07eb3a047e1e67ed63f4d5d9ae596a58fccd09bc9dc59aeb944a0c74.

Acceptance boundary

Protected signing Phase B was skipped because no real Apple Development PKCS#12 archive, password, provisioning profile, distinct private execution repository, or physical device was available. This PR does not claim a signed IPA, installation, launch, or physical-device runtime result.