Agent-resume intent forwarding reworked: live/snapshot delivery and new safeguards

What

• The internal mechanism that forwards a user's ("owner's") queued messages into a resumed agent's conversation was simplified: it no longer checks a feature-enabled config plus an owner check, and instead takes explicit resumed and contextOnly flags. When contextOnly is set, the forwarded turns are relabeled with source unattributed.
• Resuming an agent in the background now supports a liveTranscript setting that picks between live and snapshot delivery of forwarded messages; the forwarded content is spliced into the resumed agent's prompt before it continues.
• A new telemetry event fires when an agent is resumed that's flagged as an "observer" but its observer status can't be confirmed, while the CLAUDE_CODE_FORWARD_USER_INTENT setting is active. The agent_intent_forward telemetry event also gained a resumed field.

Why These changes make it more reliable for messages you send while an agent is running to actually reach that agent when it resumes, distinguishing whether they should appear as a live conversation or a one-time snapshot, and flagging cases where Claude Code can't be sure whether an agent should be treated as an observer.