UI: sidebar (280px fixed) has no defensive overflow handling beyond .sidebar-item-title #36

Problem

The workspace-detail page uses a 280px fixed-width left sidebar (.sidebar, static/css/style.css:323) containing buttons rendered by templates/workspace.html. The chat-title row inside each item is correctly truncated with overflow: hidden; text-overflow: ellipsis; white-space: nowrap at style.css:384, but:

• .sidebar-item-time (timestamp + model badge, style.css:385) has no overflow handling. A long model name with no break opportunities, or a localised date format wider than 280px, would push the sidebar item horizontally.
• .sidebar itself has only overflow-y: auto; overflow-x is default visible. Any future sidebar child that doesn't inherit truncation could break out of the 280px column.

Real-world risk is low today because current timestamp + model strings fit, but the missing guard is asymmetric with how the chat-title row is treated and is easy to regress if a future PR adds a new sidebar element.

Defensive fix is a one-line CSS rule (.sidebar { overflow-x: hidden; } or per-child truncation on .sidebar-item-time), but the choice + visual review belongs in its own PR rather than bundled into a QA task.

Severity

Low · 1 point. No user-visible bug today; flagged during the issue #28 QA pass for future-proofing.