feat(telemetry): logout flow event

[LorrisSaintGenez]

What

GROUT-351 — logout telemetry flow. Stacked on #239 (feat/auth-flow-events): it only needs the event catalog and TrackEvent helper from the auth step, nothing from the create/plan-change work.

• auth logout emits CLI Auth Logout (flow: logout) before auth.ClearToken(), while the user identifier is still attached to the telemetry metadata — the event is attributed to the user signing out.
• No event when already signed out (no logout actually happened).
• No Identify at logout time: Segment's identity graph has no concept of un-identifying — once an anonymousId is aliased to a userId, the mapping persists by design.
• Subsequent events automatically stop carrying userId: Track/Identify only set the field when the metadata has one, and after ClearToken() the next invocations load no token. Events fall back to anonymousId attribution, like a fresh install.

Test

# signed in: the final batch contains CLI Auth Logout {flow: logout}
DEBUG=1 go run ./cmd/algolia auth logout

# already signed out: no flow event
DEBUG=1 go run ./cmd/algolia auth logout

GROUT-351

[codacy-production]

Up to standards ✅

🟢 Issues 0 issues

Results:
0 new issues

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🟢 Metrics 5 complexity · 0 duplication

Metric	Results
Complexity	5
Duplication	0

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