Implement session.list_jobs / session.jobs

[nficano]

ARCP v1.1 §6.6 introduces session.list_jobs (request) and session.jobs (response) for read-only job introspection. Not implemented in Kotlin SDK.

Steps:

1. Add ListJobs and Jobs data classes in lib/src/main/kotlin/dev/arcp/messages/Session.kt, annotated with @SerialName("session.list_jobs") and @SerialName("session.jobs")
2. Register both in the MessageType sealed interface
3. Implement handler in ARCPRuntime returning the current job list with pagination cursor support
4. Add a session.list_jobs client API
5. Add tests in lib/src/test/
6. Add a samples/ListJobs/ runnable demo mirroring typescript-sdk/examples/list-jobs/

Reference: spec/docs/draft-arcp-02.1.md §6.6 and §13.3.

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Audit reference: ARCP SDK Audit v1.1 (2026-05-19)