fix(webex-core): bound services readiness by startup deadline

[robstax]

COMPLETES #N/A

No linked issue. This is an SDK follow-up to WebexServices/webex-web-client#11544.

This pull request addresses

When services.waitForCatalogInit is enabled, catalog initialization is bounded by catalogInitTimeout, but readiness finalization can subsequently wait without a timeout while credentials are refreshing. A refresh that remains in flight can therefore keep services.ready and webex.ready pending beyond the advertised startup bound.

by making the following changes

• Create one startup deadline when gated catalog initialization begins and reuse it for catalog initialization and readiness finalization.
• Wait for an in-flight credential refresh only until the remaining startup deadline, then release services readiness.
• Recheck refresh state after registering the listener and remove the listener after either refresh completion or deadline settlement.
• Apply the same contract to Services V1 and Services V2.
• Add focused tests for hung refreshes, normal refresh completion, deadline settlement, and listener cleanup.

Change Type

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update
• Tooling change
• Internal code refactor

The following scenarios were tested

• yarn workspace @webex/webex-core build:src
• yarn workspace @webex/webex-core test:unit --targets services/services.js — 78 tests passed.
• yarn workspace @webex/webex-core test:unit --targets services-v2/services-v2.ts — 81 tests passed.
• yarn lint:staged — ESLint passed for all four changed files.
• Webex Web Client signed-in Playwright regression with the feature enabled and both catalog and refresh requests held open — startup was released at the shared deadline.
• Webex Web Client signed-in Playwright negative case with the feature disabled — existing immediate-ready behavior was preserved.
• The same Playwright test against the previously published SDK reproduced the regression: enabled failed at services.ready; disabled passed.

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• This PR is related to
  • Feature
  • Defect fix
  • Tech Debt
  • Automation

I certified that

• I have read and followed contributing guidelines
• I discussed changes with code owners prior to submitting this pull request
• I have not skipped any automated checks
• All existing and new tests passed
• I have updated the documentation accordingly

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