feat(ui): apply current-ref Apple Design states

[VincentAdamNemessisX]

Summary

• add a semantic, fail-closed state model shared by Android Save Sync presentation
• add an always-visible macOS converter safety card with reduced-motion/transparency, increased-contrast, and VoiceOver behavior
• add macOS menu-bar accessibility labels, localized state copy, tests, and a source-built UI screenshot

Verification

• swift test (MH3G converter): 43 tests passed
• swift test (macOS Save Sync): 17 tests passed
• Android JDK 17: assembleDebug testDebugUnitTest lintDebug passed
• Rust converter: 205 tests across 8 suites passed
• converter asset + Windows source contract checks passed
• packaged macOS converter synthetic smoke passed
• git diff --check passed

Boundaries

• no real save, ROM, game, ADB, or formal application data was used
• no format/protocol/restore contract change
• Hosted Windows publish and Android device install are not claimed by this UI slice

Supersedes stale PR #9, which predates current v0.0.11 main.