Add Claude CLI observability logs

[laotoutou]

Summary

• add wrapper-level observability around Claude CLI process spawn, first stdin write, first stdout byte, and first stdout line
• add Codex app-server observability around process spawn, first stdin write, first stdout/stderr lines, initialize, thread, turn, first notification, first codex event, and first user-visible event
• keep vendor process instrumentation in wrapper-owned code without patching vendored dependencies
• add focused tests covering the new structured logs

Testing

• node --test test/claude-runtime.test.js
• node --test test/codex-runtime.test.js
• node --test