Improve Kanban notification readability

[houenyang-momo]

Summary

• make Kanban terminal notifications lead with friendly board labels instead of task IDs
• include multi-line completion summaries instead of truncating to the first 200 chars
• keep the task id as a low-priority Ref line for debugging

Test plan

• /usr/local/lib/hermes-agent/venv/bin/python -m pytest tests/gateway/test_kanban_notifier.py -q
• /usr/local/lib/hermes-agent/venv/bin/python -m py_compile gateway/run.py /opt/athena/hermes-home/profiles/athena-master/hooks/athena-topic-kanban-intake/handler.py

[teknium1]

Thanks for the focused notification-readability improvement. The underlying problem remains on current main: completed notifications still truncate to the first 200 characters and lead with Kanban <task-id> (gateway/kanban_watchers.py:354-366).

Problems

• The notifier was extracted from gateway/run.py into gateway/kanban_watchers.py by 1c68f6f81; the live formatter is now at gateway/kanban_watchers.py:337-407, so the replacement needs to be applied there.
• Current main also sends status events (gateway/kanban_watchers.py:167, 394-398). The submitted formatter has no status branch and returns None for unsupported kinds, so porting it directly would silently suppress those notifications.

Suggested changes

• Move the formatter/board-name collection into gateway/kanban_watchers.py and preserve a human-readable status message.
• Add a notifier-path test for a named board and a status event; the submitted test exercises only the formatter helper.

Automated hermes-sweeper review.