fix: improve Grid.js table header alignment and column min-width

- Add default minWidth (100px) to all grid columns via normalizeGridColumns
  to prevent header truncation when data entries are short
- Fix inconsistent th heights by setting .gridjs-th-content line-height
  to 24px (matching the sort button height) so sortable and non-sortable
  columns render at uniform height
- Remove dead button.gridjs-sort height:15px rule (was overridden by 24px)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

web/js/core/app-grid-factory.js

@@ -55,6 +55,8 @@ const uniqueColumnId = (candidate, usedIds, fallbackPrefix = 'col') => {
   return next;
 };
 
+const DEFAULT_MIN_WIDTH = '100px';
+
 const normalizeGridColumns = (columns, sortColumns) => {
   const source = Array.isArray(columns) ? columns : [];
   const sortKeys = Array.isArray(sortColumns) ? sortColumns : [];
@@ -69,7 +71,11 @@ const normalizeGridColumns = (columns, sortColumns) => {
     const label = typeof baseColumn.name === 'string' ? baseColumn.name : '';
     const fallback = `col_${index + 1}`;
     const id = uniqueColumnId(explicitId || sortKey || label || fallback, usedIds, fallback);
-    return { ...baseColumn, id };
+
+    const skipMinWidth = baseColumn.hidden || baseColumn.plugin || baseColumn.minWidth;
+    const minWidth = skipMinWidth ? baseColumn.minWidth : DEFAULT_MIN_WIDTH;
+
+    return { ...baseColumn, id, ...(minWidth ? { minWidth } : {}) };
   });
 };