Prevent abort listener leaks in async client requests

[minggangw]

This PR tightens Client.sendRequestAsync() resource cleanup by ensuring abort/timeout listeners are removed in all completion paths (success, abort, timeout, and synchronous failures), preventing listener accumulation across repeated async requests.

Changes:

• Add explicit cleanup of abort/timeout listeners in sendRequestAsync() via shared cleanup() + named handlers.
• Add tests that assert abort/timeout listeners are fully released after each request outcome (including pre-aborted signals and send/serialization failures).

Fix: #1596

[Copilot]

🟢 Approval recommended

The change is small, targeted, and backed by new tests that verify listener cleanup across the relevant success and failure paths.

Pull request overview

This PR tightens Client.sendRequestAsync() resource cleanup by ensuring abort/timeout listeners are removed in all completion paths (success, abort, timeout, and synchronous failures), preventing listener accumulation across repeated async requests.

Changes:

• Add explicit cleanup of abort/timeout listeners in sendRequestAsync() via shared cleanup() + named handlers.
• Add tests that assert abort/timeout listeners are fully released after each request outcome (including pre-aborted signals and send/serialization failures).

File summaries

File	Description
lib/client.js	Ensures abort/timeout listeners are consistently removed on resolve/reject to avoid listener leaks.
test/test-client.js	Adds coverage asserting listener cleanup across success, abort, timeout, and error scenarios.

Review details

• Files reviewed: 2/2 changed files
• Comments generated: 0
• Review effort level: Lite

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[coveralls]

coverage: 90.831% (+0.02%) from 90.812% — minggangw:fix-1596 into RobotWebTools:develop