Bug description

When an incident has a long summary, the "Incident" column in the incidents table stretches horizontally beyond the viewport, breaking the layout.

Root cause

Two problems:

1. FormattedContent renders summary as HTML via dangerouslySetInnerHTML. The resulting DOM contains block-level elements (<p>, <ul>, etc.) which create their own block formatting context. line-clamp on the outer container does not penetrate into these child block elements, so the text is never clamped.

2. The table cell (<td>) for the "Incident" column has no overflow constraint, so it grows with the content and stretches the entire table.

How to reproduce

1. Have an incident with a long AI-generated summary
2. Open the Incidents list page
3. The table stretches beyond screen width

Expected behavior

The summary column should have a bounded width. Long summary text should wrap and be truncated with ellipsis after 2-3 lines.

Related: #3438