feat(sentinel): emit lifecycle events

[raashish1601]

Summary

Fixes #3012.

createSentinel() exposes isOpen and isReady, but it did not emit the lifecycle events that standalone clients expose. This adds connect and ready emissions after Sentinel finishes connecting, and emits end after closing or destroying an instance that was open.

The change is additive and keeps the event ordering aligned with the state a Sentinel consumer can observe.

Validation

• .\node_modules\.bin\tsc.cmd --build packages/client --force --verbose
• npm run lint:changed
• git diff --check

Note: the focused Sentinel mocha test could not run locally because Docker is not installed in this Windows environment (spawn docker ENOENT).

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Note

Low Risk
Low risk additive behavior change: emits connect/ready after successful RedisSentinel.connect() and emits end on close()/destroy() when previously open; could affect consumers that assume no events or different ordering.

Overview
RedisSentinel now emits lifecycle events consistent with standalone clients: connect and ready are emitted after connect() completes, and end is emitted after close() or destroy() when the instance was previously open.

Adds a focused sentinel test (lifecycle-events.spec.ts) asserting the connect → ready → end event sequence and that end is observable via once() after shutdown.

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