Clarify Claude Code monitor delivery verification

[tomohisa]

Summary

Closes #269.

This clarifies the difference between monitor delivery being configured and Claude Code's generic Monitor tool actually running in the current session.

Changes

• Document that delivery.sh status showing mode: monitor is configuration status, not runtime success.
• Add Claude Code monitor verification steps to the README: ToolSearch select:Monitor, Monitor(agmsg inbox stream), footer 1 monitor, and transcript Monitor event: "agmsg inbox stream".
• Call out failure states: footer 1 shell, Bash/background/nohup watch.sh, Azure/MCP/other monitor-branded tools, and missing generic Monitor tool.
• Update the Claude Code skill prompt and SessionStart/delivery directives so agents do not treat a background shell watcher as successful realtime monitor delivery.
• Add the Windows Git Bash note for Claude Code monitor delivery and PowerShell/native-shell retry guidance.

Validation

• git diff --check
• bash -n scripts/delivery.sh scripts/session-start.sh scripts/drivers/types/claude-code/_delivery.sh
• npm test
• manually checked delivery.sh set monitor + delivery.sh status output in a temporary project

Bats was not run locally because the bats runner is not installed in this environment.