FetchPolecats() was showing all tmux sessions system-wide without
filtering by the workspace's registered rigs. This caused unrelated
refineries (like roxas) to appear in the dashboard.
Now loads rigs.json and only displays sessions for registered rigs,
matching the filtering behavior already used in FetchMergeQueue().
Fixes gh-868
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
232fc79cd5