fix(agents-core): process listeners

[rossrobino]

Summary

Ensures cleanup occurs and exit occurs for each provider.

Test plan

I tested on the basic example, pressing ^c while the agent processed.

Issue number

Fixes #44

Checks

• I've added new tests (if relevant)
• I've added/updated the relevant documentation
• I've run pnpm test and pnpm test:examples
  • (If you made a major change) I've run pnpm test:integration (see details)
• I've made sure tests pass
• I've added a changeset using pnpm changeset to indicate my changes

[changeset-bot]

🦋 Changeset detected

Latest commit: 8858b6c

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 5 packages

Name	Type
@openai/agents-core	Patch
@openai/agents-openai	Patch
@openai/agents-realtime	Patch
@openai/agents	Patch
@openai/agents-extensions	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR