feat: make node agent keep-alive settings configurable

[itsmeadi]

Summary

• add configurable Node agent options to ClientOptions (keepAliveMsecs, maxSockets, maxFreeSockets, scheduling, httpAgent, httpsAgent)
• keep backward-compatible defaults by continuing to use keepAlive: true and keepAliveMsecs: 3000 when overrides are not provided
• add unit tests verifying default behavior, custom option propagation, and custom agent injection

Test plan

• STREAM_API_KEY=dummy STREAM_API_SECRET=dummy yarn mocha --require tsx/cjs --require dotenv/config test/unit/node/client_test.js
• CI passes

Made with Cursor

[github-actions]

Size Change: +9.61 kB (+8.78%) 🔍

Total Size: 119 kB

📦 View Changed

Filename	Size	Change
dist/js_min/getstream.js	38.6 kB	+3.03 kB (+8.54%)	🔍
dist/js/getstream.js	80.5 kB	+6.58 kB (+8.9%)	🔍

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