Fold ctx.notifyNative into a ctx.os namespace so every way a plugin
reaches outside the app window lives behind one attributed door instead
of accreting one top-level ctx method per capability:
- ctx.os.notify — the native-notification door from the previous commit,
unchanged semantics (plugin kind pref, away-gating, per-plugin throttle).
- ctx.os.openExternal / ctx.os.revealPath / ctx.os.writeClipboard — the
existing window.hermesDesktop bridge capabilities, now sanctioned and
result-shaped: each resolves false (never throws) when the bridge or
member is missing, so a plugin branches on the result instead of
sniffing the preload surface or crashing on an older shell.
No new Electron surface: everything routes through bridge members the
app already ships; the notification path keeps every existing gate.
e8ccb4a2ea