Replaces the stale Auto-Launch section with an accurate description of the
Tasks 3–7 implementation: OS-authoritative read model, platform-specific
applyLoginItemSettings() contract, Linux/AppImage-only conditional re-apply,
defence-in-depth hidden-launch detection, and the pure helpers in autoLaunch.ts.
Also updates Startup Sequence step 9 to reflect that unconditional re-apply is gone.