Fix Slack bot_message event handling

[rapythe-cmyk]

Summary

• Allow Slack message events with subtype=bot_message through the Socket Mode filter.
• Tighten other-bot detection so it relies on bot_id or bot_message, not user.startswith("U").
• Add token-free regression tests for event filtering and actor classification.
• Update install docs so the new helper module is copied with the daemon.

Why

Previously, the Socket Mode listener ignored all messages with a subtype. Slack bot messages commonly arrive as subtype=bot_message, so dialog-channel bot-to-bot discussion mode could drop those events before handle_message() saw them.

The old is_other_bot logic also treated non-target human users with U-prefixed Slack IDs as other bots. The new helper keeps normal human users from being misclassified while still ignoring the daemon’s own bot messages.

Checks

• python3 -m unittest tests/test_slack_jipsa_event_filter.py
• python3 -m py_compile templates/scripts/slack-jipsa/daemon.py
• python3 -m py_compile templates/hooks/append_turn_raw.py templates/lib/notion.py templates/lib/slack_mrkdwn.py templates/lib/md_to_notion.py
• python3 templates/lib/slack_mrkdwn.py
• git diff --check

Note: py_compile was run with PYTHONPYCACHEPREFIX=/private/tmp/agent-bootstrap-pycache on this sandboxed macOS environment so bytecode cache writes stayed inside an allowed temp directory.