Mobs data listing cleanup

[ArtTrail]

The empty list has column headers that are cut off. And when the list has data, the Object column data is cut off.

[ArtTrail]

Fixed both halves: the empty-list header clipping was caused by the Weather column using star-width sizing, which Avalonia's DataGrid only resolves correctly against actual rows — with zero rows the header collapsed. Switched it to a fixed width. Object-column truncation was caused by the list's existing auto-sizer (which recalculates column widths from real fetched data) using a per-character width estimate that was too tight for the rendered font — widened it so longer target names fit.