Phase 3 d.1: relocate plugin + interactor + interactions under src/platforms/apple

[thymikee]

Relocate the plugin + Apple interactor + interactions leaf under src/platforms/apple/, making getInteractor's core → platforms routing the final shape.

Move

• src/core/platform-plugin/{plugin,register-builtins}.ts → src/platforms/apple/ (the registry; keep the registry generic, the Apple plugin instance is the first real consumer)
• src/core/interactors/apple.ts → src/platforms/apple/interactor.ts
• src/platforms/ios/interactions.ts → src/platforms/apple/ (it is the Apple interaction dispatcher leaf — branches iOS synthesized gesture :264/:270/:284, tvOS remote-press :333, macOS desktop-scroll :350-358; not iOS-only)
• Populate the b.3 providers/recording/appLog/perf facets here.

Blocked by

b.3 (facets ready so daemon → platforms stays the legal arrow). Until then the registry stays in core/.

Refs

perfect-shape.md §5.1; ADR-0009. (Phase 3 step d.1.)

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Part of #972 (Phase 3 — Apple PlatformPlugin).