fix(viewer): use ghost span in grid stack to enforce column name width

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web/static/view.css

@@ -339,9 +339,24 @@ body {
   color: var(--muted);
 }
 
+.col-filter-wrap {
+  display: grid;
+}
+
+.col-filter-wrap > * {
+  grid-area: 1 / 1;
+}
+
+.col-filter-ghost {
+  visibility: hidden;
+  white-space: nowrap;
+  font: inherit;
+  pointer-events: none;
+  padding: 2px 4px;
+}
+
 .col-filter-text {
   width: 100%;
-  min-width: 40px;
   border: 1px solid transparent;
   border-radius: 3px;
   padding: 2px 4px;