Enable macOS settings, notifications, OPC and label features

[Guffawaffle]

Enables Mod Settings, OPC fleet highlights/countdowns, configured desktop notifications, and fleet/galaxy label controls on macOS. Fleet labels can switch from Native during play; galaxy controls include major/minor label profiles and combined overlays. Existing opt-in defaults remain unchanged. Runtime settings persistence now also runs on Mac, using the existing config path and background writer, with normal-quit draining and save-failure notices.

New Mac hook families validate exact entries in the loaded Mach-O function table and use SPUD's bounded instruction decoder. Fleet and galaxy share one LOD detour; failed validation leaves the affected controls unavailable. The small galaxy selection callback allows a shorter verified function extent while still decoding the complete architecture-specific overwrite. Partial fleet/OPC installations keep custom behavior inactive.

Desktop alerts use the game's UserNotifications identity, request permission only when desktop events are configured, preserve its notification delegate, and leave sound selection to existing audio settings. Includes the two fleet-arrival corrections from the tested Mac audio stack and runs their regression fixture through both platform test runners.

Validation: local Windows release build and config-save fixtures passed, including disk reload and an immediately pending slider write. Windows, Mac ARM64, Mac x86_64, and Mac packaging CI passed for candidate 92f6e446 in run 35414990583. The Mac ARM tester confirmed notifications/OPC, WARP course text, galaxy multi-select/zoom labels, and settings persistence after restart. Intel Mac runtime testing remains unconfirmed; its evidence is CI/build coverage. The hotkeys-disabled and immediate-slider-quit native paths are documented follow-up checks, not separately claimed user smoke.

This remains the combined candidate for eventual play promotion. Confirmed work has also been carried into the current upstream feeder PRs, including settings controls #282, fleet notifications #268, galaxy labels #293, and OPC indicators #294. Those feeder reviews added a Mac node-depletion preflight correction; reconcile subsequent source fixes before promoting this candidate. This backlog cleanup does not merge or deploy the branch.

[Guffawaffle]

Superseded by #299. Its refreshed branch retains every commit from this PR, incorporates the Mac shortcut/settings integration from #302, and adds the newer node-depletion hook validation. Continue review, CI, and runtime qualification on #299; this branch is retained for history.