KindaVim telemetry has no app-quit flush hook (~5s loss on force-quit)

[malpern]

Tier: 3 (minor polish)

From the pre-release feature-gap audit.

Problem

The KindaVim telemetry store flushes on a timer (default ~5s) and skips a final flush in deinit (MainActor restriction), so up to ~5s of aggregate counters are lost on force-quit or when telemetry is turned off mid-session.

Evidence

• Sources/KeyPathAppKit/Services/KindaVim/KindaVimTelemetryStore.swift:165-170 — deinit skips final flush; line 169 notes "app-deactivation hook (TODO in a follow-up)".

Suggested fix

Add an app-deactivation / will-terminate flush hook.